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]]>**Former BGSMath Director Marc Noy receives the Narcís Monturiol Medal**

The Government of Catalonia (Generalitat de Catalunya) bestowed the prestigious Narcís Monturiol Medal upon UPC professor Marc Noy, former Director of BGSMath. The Medal is awarded since 1982 by the Catalan President to distinguished institutions and scholars who gave a special contribution to science or technology in Catalonia.

This year’s awardees are 19 in the most diverse fields of knowledge, plus one institution: CERCA, the group of centres of excellence based in Catalonia (the full list is available here). “I feel very honoured,” said Noy. “I think it is a recognition not only to my scientific career, but also to my contribution in the consolidation of the BGSMath”.

Noy’s research interests are in Discrete Mathematics, particularly in combinatorics, graph theory, and probabilistic methods. He leads the Geometric, Algebraic and Probabilistic Combinatorics Lab and is full professor at the Department of Mathematics at UPC. In 2012 he received the Alexander Humboldt Research Award for his achievements in Discrete Mathematics and was the BGSMath Director between 2015 and 2018. He still holds the position of Scientific Director of the BGSMath – María de Maeztu Unit of Excellence.

The Generalitat made the decision public on 12 September and the ceremony will take place in the next weeks at the Palau de la Generalitat, in Barcelona.

Participants

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]]>The post Una ley matemática podría anticipar la posibilidad de extinciones masivas en los ecosistemas appeared first on BGSMath.

]]>**Una ley matemática podría anticipar la posibilidad de extinciones masivas en los ecosistemas**

Las bifurcaciones son un fenómeno matemático que permite describir cambios cualitativos en la dinámica de un sistema cuando un parámetro de control cambia. Por ejemplo, en un modelo de crecimiento de una población de bacterias podemos tener supervivencia o extinción; uno de estos dos estados puede darse al cambiar la tasa de mortalidad, que hace de parámetro de control.

Las bifurcaciones se encuentran en una gran cantidad de fenómenos físicos, reacciones químicas, láseres, experimentos de laboratorio con células, modelos climáticos, en modelos matemáticos de ecosistemas, etcétera. Sin embargo, en los modelos matemáticos, las bifurcaciones explican la dinámica del sistema en el régimen estacionario, es decir, considerando su evolución durante un tiempo infinito. En las situaciones naturales, el tiempo observable es siempre limitado.

Un grupo interdisciplinar de científicos de la Universitat Autònoma de Barcelona (UAB), del Centre de Recerca Matemàtica (CRM) y de la Barcelona Graduate School of Mathematics (BGSMath), formado por un matemático, un físico y un biólogo y financiado por la Fundación “la Caixa”, ha encontrado unas fórmulas generales que permiten describir las bifurcaciones de modo más realista, es decir, no a tiempo infinito sino para tiempos finitos, alcanzables en la práctica.

“Las fórmulas matemáticas identificadas son universales y nos permitirán hacer predicciones muy concretas sobre los fenómenos que estamos observando y si se están acercando a una bifurcación”, explica Josep Sardanyés, uno de los tres autores del artículo. “Para fenómenos como la extinción de una especie, o el cambio climático, solo podemos observar la evolución en un tiempo limitado. Gracias a nuestro método, nos bastan estos datos a tiempos cortos para establecer si un dado sistema acercándose a un cambio tendrá una bifurcación ‘suave’, es decir gradual, o una bifurcación ‘catastrófica’, es decir que llegará a un punto que generará un cambio de fase abrupto e irreversible”.

Dicho de otra forma, las leyes descritas por los investigadores en este trabajo permitirán dar “señales de alerta” (“warning signals”) mediante el análisis de series temporales finitas, como es el caso de las obtenidas para sistemas ecológicos, antes de que un evento catastrófico irreversible (una extinción, o una reacción química extrema, o el deshielo de las capas polares, etcétera) tenga lugar.

Estas fórmulas presentan universalidad, es decir, aunque la ecuación que describe un fenómeno sea complicada, si en ella subyace una cierta bifurcación, su descripción a tiempo finito será única y además sencilla.

El fenómeno de la bifurcación presenta también “auto-similitud”, de tal manera que la descripción a un tiempo dado es una réplica “escalada” de lo que pasa a otro tiempo. Esta propiedad es análoga a lo que se da en las transiciones de fase termodinámicas, en concreto cerca del llamado punto crítico.

En el estudio, publicado en la revista *Scientific Reports* del grupo *Nature*, han participado Álvaro Corral, investigador del Centre de Recerca Matemàtica, de la Barcelona Graduate School of Mathematics, del Departamento de Matemáticas de la UAB y del Complexity Science Hub de Viena; Josep Sardanyés, del Centre de Recerca Matemàtica y de la Graduate School of Mathematics; y Lluís Alsedà, del Departamento de Matemáticas de la UAB y de la Barcelona Graduate School of Mathematics. La investigación ha sido financiada por la Fundación “la Caixa”.

Participants

CRM

BGSMath

Tel: +34 93 586 8521

alvaro.corral@uab.cat

CRM

BGSMath

BGSMath

Director – CRM

UAB

BGSMath

llalseda@crm.cat

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]]>The post CAFE will train 12 young scientists to tackle extreme weather events appeared first on BGSMath.

]]>CAFE will train 12 young scientists to tackle extreme weather events

Sudden heat waves or devastating floodings; catastrophic draughts or unexpected super storms. Climate change has accustomed us to the rising costs of extreme weather events. Nowadays, we can barely predict them when they are about to happen.

But all of this could change, thanks to a new H2020 project (Innovative Training Network) coordinated by CRM researcher and BGSMath Faculty member Álvaro Corral.

“The most important problems humanity is facing in the 21st century,” says Corral,” have to do with our incapacity to understand, predict, and manipulate complex systems. Extreme weather events can be a consequence of climate change and they are the perfect example of how a complex system works. To limit their catastrophic consequences, we need to learn how to model them,” he says.

ITNs are training programs within the Marie Skłodowska-Curie Actions (MSCA) that aim “to train a new generation of creative, entrepreneurial and innovative” young researchers, according to the official definition of the European Commission, “able to face current and future challenges and to convert knowledge and ideas into products and services for economic and social benefit.”

One of these challenges with an enormous economic impact is clearly improving climate and weather forecasts on the subseasonal scale, one that is between weather forecast and climate change predictions. Mitigating damage and enabling prevention in the transport, agriculture, energy and tourism sector on a timescale that goes from ten to ninety days would be the most obvious long-term benefit for society.

“Climate and natural disasters have something in common: the distribution of probability follows similar statistical laws. That is, extreme events are very rare but have an important impact on the system,” explains Corral.

The problem with subseasonal predictions is that we have a poor understanding of the phenomena that affect the predictability at this time scale.

The ITN coordinated by Corral is called CAFE (Climate Advanced Forecasting of sub-seasonal Extremes – Project “813844 — CAFE — H2020-MSCA-ITN-2018”) and brings together ten organizations from across Europe plus the Universidad de la República in Uruguay. Besides the CRM itself, the other European organizations are the Potsdam Institute for Climate Impact Research, the Max Planck Institute for the Physics of Complex Systems, the Technische Universität Bergakademie Freiberg (all three in Germany), the Spanish Consejo Superior de Investigaciones Científicas (CSIC), the UPC, the French forecast agency Météo-France, the French company ARIA Technologies, and the European Centre for Medium-Range Weather Forecasts (ECMWF). The CAFE consortium is completed by another 11 partners, who will contribute to training 12 young researchers in climate science, meteorology, statistics and nonlinear physics. Two CAFE young researchers will be at CRM and will soon join the BGSMath PhD-student community.

“The objective of the CAFE network is to improve the predictions by merging expertise in different fields, as well as ensure translation to users, through the participation of government agencies and industry. Most of us are experts in nonlineal phenomena. Working side by side with meteorologists and climatologists will ensure that the field moves significantly forward,” explains the coordinator.

Mulidisciplinarity and academia-industry interaction will be fostered by the provision that students’ theses will have to be supervised by scientists in more than one institution. These young researchers will be given top-level training not only by their respective universities, but more specifically through a thorough programme organised by the consortium. The CAFE Programme encourages researchers to gain experience in different working environments, while developing transferrable skills, such as speaking in public, science communication, or innovation management.

One of the industrial partners in CAFE is the German insurance multinational Munich Re, that will co-supervise one of the students to work on extreme weather anomalies related to ENSO, the El Niño Southern Oscillation, a periodic variation in winds and sea surface temperatures over the tropical eastern Pacific Ocean and that cause a number of important damages on the ground.

BGSMath Research Manager Arantxa Sanz has aided Corral and the researchers shape the ITN consortium and proposal. “Mathematical modelling is key to tackle the most urgent challenges humanity is facing,” she says. “At BGSMath, we are in the right place to provide top-level international expertise that can contribute to significant advances for society.”

“Thanks to the Network,” emphasises the CAFE coordinator, “we will train a new generation of brilliant researchers; one that will have a background in climate, meteorology and in nonlineal phenomena, who will also be able to work for private companies. All-round top-quality professionals that today are very difficult to find on the market.”

Participants

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]]>The post “This guy will win a Fields Medal!” appeared first on BGSMath.

]]>“This guy will win a Fields Medal!”

The first time I met Alessio Figalli was in a summer school in Ischia in 2011, during my first year as a PhD student in Barcelona. He was giving a course on free boundary problems, the topics on which I later worked with him for several years.

One of the things that I remember from that week in Ischia was Francesco Maggi talking about Alessio and saying “This guy will win a Fields Medal.” I started working with Alessio in 2014, when I arrived at UT Austin as a new postdoc. Something that anyone can see when talking to him is that he is a very friendly and down-to-Earth person. But then, when discussing math with him, one realises immediately that he is also brilliant and extremely fast – way faster than anyone else I have ever discussed math with.

It is incredible how quickly he can catch up new ideas or read complex math papers, this is still surprising for me! Even though he is much faster than others, he is always receptive to different ideas, is supportive and encouraging, and never condescending. Moreover, he has always good advice for younger researchers, and is very helpful and generous with his students and postdocs.

On the personal side, I enjoyed very much his birthday parties in Austin, where several professors, postdocs, and visitors would have a BBQ at his backyard, and stay there until late evening. After my time as a postdoc at UT Austin I moved to Zurich, where he is a professor at ETH. Now that we’re in Zurich, I enjoy very much having lunch with him and Joaquim Serra at the ETH terrace, and discussing math in his office.

I always thought that he should and would probably win the Fields Medal, and I was really happy to find out this summer that Francesco was indeed completely right! *(Author: Xavier Ros-Oton)*

Participants

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]]>Meet the partial differential equations tamer

BGSMath alumnus Xavier Ros-Oton has recently been awarded an ERC Starting Grant, which comes with an allocation of more than one million euros for five years. His project, called EllipticPDE, is entitled “Regularity and singularities in elliptic PDEs: beyond monotonicity formulas.”

The European Research Council this year received 3,170 applications. Only about 13% of the applicants received funding. Ros-Oton, who currently works at the University of Zurich, is the only Spanish national in this round to have received one of the 11 ERC Starting Grants given to mathematicians throughout Europe. He is also the youngest of all ERC awardees in 2018.

This mathematician, who obtained his PhD in 2014 at the UPC with Xavier Cabré, has an impressive CV for a 30-year old scientist. One of the most cited mathematicians in his field, he held positions in universities in US and Europe, and collected many prizes and awards, among which the Antonio Valle Prize of the Spanish Society of Applied Mathematics and the J. L. Rubio de Francia Prize of the Spanish Royal Mathematical Society, two very prestigious recognitions awarded to brilliant young mathematicians.

*Penta* met Xavier when he visited Barcelona, in the spring, for a colloquium at the Faculty of Mathematics and Statistics of the UPC. “I always feel very welcome in Barcelona,” he said. He likes to define the equations he works on, Partial Differential Equations (PDEs for short), “the equations that move the world”. The reason for this is that not only do they solve centuries-old classical physics problems, such as the distribution of heat in a room, or how waves in a pond move after you throw a stone, or what is the shape of an electrostatic field, but they are also applicable to very different fields, such as biology (how does an invading population evolve?), finance (how does the price of a financial product evolve?), weather (how are the winds going to evolve?), or engineering (how to simulate the aerodynamics of a plane?). PDEs also appear in many pure math problems in analysis, geometry, or probability.

“PDEs are an exciting field to work in because we have a lot of questions to answer,” he says. “They are very interdisciplinary and we have work for years to come!”.

Ros-Oton’s pet problem is called Stefan’s Problem, dating back to 1831. In a nutshell, it’s the PDE that models the transition from water to ice and vice versa. In other words, it describes how ice melts. Technically, this problem belongs to a class of problems called “free boundary problems.” The same type of equations is also applicable in other fields, “as is often the case”, points out the young mathematician. “Finance, fluid mechanics, even pure mathematics. Mathematically, they are all the same problem. A very difficult one, but once you have some answers, you can apply them to a lot of different fields,” he says.

As anyone who attended one of his classes knows, Xavier likes to teach. “But I also want to have enough time for my research,” he emphasises.

**How did you decide to become a mathematician?**

Actually, I only decided my university career the year before the end of high school. Before, I had always liked maths and science, but wasn’t sure on what to do. Engineering was one option at the time. But in the last year of high school, I took part in the Math Olympiads and other competitions, and that helped me to choose maths. And now I am happy of the decision!

**So happy that you were the fastest to get a degree.**

Indeed, I quickly realised I could go faster than others and that I could be over before time. I asked the Dean if it was possible to skip one year, and they allowed me.

**How do you manage the flattering opinions people tend to have about precocious mathematicians?**

You always have to keep in mind that you are not the only one. You are never the smartest in the world. And if you work with smart people, this helps you to be humble. I always encountered many smart people throughout my career, and this has helped me a lot.

**Does one have to be a genius to do mathematics?**

A famous mathematician, Terry Tao, says that ‘the answer is an emphatic no’. I agree with him. It’s neither necessary nor sufficient. A great deal of math research is just being able to ask the right questions. It’s not enough to be very smart or a genius, you need to work on interesting problems. Of course, it helps that you are good at maths. But it’s far more important to be surrounded by good people. You can do very good science without being Tao.

**You are a very extroverted person. Does that help?**

If you are very solitary, or introverted, it is more complicated to speak with people. Travelling, collaborating, talking to people helps a lot in this field. There are of course examples of very weird mathematical geniuses, but most of us are not like that.

**What’s the best way to face a new mathematical problem?**

It really depends. Usually what you have to do, again, is to talk to many people. This can help you to ask the right question, or discover if other people have already tried to answer, and how. Of course, the more famous the problem or the conjecture is, the easier it is that someone has already tried to solve it. And probably, the harder it is to solve. Sometimes the question comes to you while you are working on something else. And you realise the question you have is much more general than you thought. Sometimes you do have brilliant ideas, but eureka moments are not that frequent.

**You have been awarded many prizes and obtained consistent funding. How does a mathematician spend his research money?**

Strictly speaking, to work I just need a blackboard and a computer. Most of the funding we have is used to travel. Travelling to conferences and meeting colleagues is very important for us. Mathematics, unlike what people think, is a very collaborative science. We also organise conferences, and we have to pay for travel costs for the speakers. And of course, once you start to have your own money and set up a group, you need to pay for the salaries of your students or postdocs.

**Any advice for your young colleagues? **

First of all, talk to the good people. Many of them. Try to think about problems they are working on. Also, make the effort to have a global vision of the field you are working on, don’t limit yourself to the tiny sector you are more specialised in. Be ready to change problem or even subject if you think another one is more promising. Also, keep in mind difficult problems all the time. You don’t need to be able to solve them, but don’t be afraid of the challenge. One needs to be realistic, but also ambitious. Finally, try to have a life outside maths. I like to go to the mountains and to play basket. Find your own hobby: keeping your mind free is healthy, also for your math!

Participants

“The equations that move the world” – interview by BBVA Foundation (in Spanish)

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]]>The post The geometry that solves every day’s problems appeared first on BGSMath.

]]>The geometry that solves every day’s problems

Mathematics peeps out in the most unexpected ways. Say, when you have to draw a metro map. Or when you have to plan your next trip to multiple cities. Or maybe while you are enjoying an origami. Or when you have to 3D-print your favourite cup – well, when that becomes available to most people, at least. Even if you want to avoid train wagons colliding.

Rodrigo Silveira and Vera Sacristán, researchers at the UPC and BGSMath Faculty members, recently organised an Intensive Research Programme that deals with all of these problems – and much more. The programme in Discrete, Combinatorial and Computational Geometry took place at the CRM during 8 weeks between April and June 2018.

An Intensive Research Programme is “an occasion to learn, and perform research together,” to put it in Sacristán’s words. In this case, Vera and Rodrigo had put together more than 120 experts (nearly half of them, PhD students) from 19 countries in hot topics in discrete combinatorial and computational geometry – overarching topics that encompass a number of different related fields.

The research programme consisted of four different courses, and 12 different 2-hour long “inspiring lectures”, together with structured moments for participants to actively interact and do research together trying to solve open problems.

Approximation algorithms for geometric problem were at the centre of one of these courses. “There’s a famous classical example where approximation algorithms can play a role, the so-called Travelling Salesman problem,” explains Rodrigo. “How to minimise the route a salesman has to cover to visit each city and go back to the original city? Believe it or not, mathematicians do not have an efficient algorithm to solve this simple problem exactly. We can proceed geometrically, and we can maybe find a solution that is within, for example, 10% of the right one. In one of the courses, we studied these approximation algorithms,” he says.

Computational topology was another hot topic of the programme. While topology is the science that studies the deformation of geometrical objects, computational topology for example helps a 3D-printing computer to establish how to “connect” a finite set of dots in space, the input of a 3D scan. The computer has to figure out whether, say, it was a cup (with a “hole” for the handle) or a box – no holes. “The system has to figure out how points are connected to each other, how ‘persistent’ is the topology, as we say. Basically, we need to know how many holes it has”, explains Vera. Among mathematicians there’s a common joke that goes: “a topologist is someone who cannot distinguish between a donut and a cup.” The “topological” reason is clear in the image here.

Designing “optimal” graphs on a surface and the study of their intersections (themes of two other courses of the Research Programme) have some very interesting practical applications, and a sad anecdote. During World War II, in 1944, Hungarian mathematician Pál Turán was forced to work in a brick factory by the Nazis. Enslaved workers had to put bricks on small wheeled trucks to take them to storage yards. The problem was that at rail crossings generally trucks jumped off the rails, causing bricks to fall. The problem he immediately saw with mathematical eyes was: how to minimise the number of intersections? “This is a much deeper problem than it seems,” clarifies Vera. “We spent 5 days of one of the courses talking about graphs on surfaces, and how to connect vertices and edges.” An interesting and also historical application of this is in the design of maps, especially metro maps: it is far less obvious than it seems to guarantee the readability of all the station names if the network is dense.

“Our philosophy,” says Sacristán, “was to leave much room for participants to work with the lecturers on open problems in maths. New collaborations grew, and I am sure we will see some interesting publications arising soon from these working sessions.” As a sign of further interaction, many of the participants also ended up giving short seminars on their research fields.

“A very interesting aspect of the programme”, adds Rodrigo, “is computational geometry toward applications. We dedicated some lectures to this issue. For example, on geometric folding. In other words: origami. Origami has a very interesting set of industrial applications: say you want to produce a flat object that you later need to fold. These studies give you tools to understand if you can do it or not. Or say you want to inject a folded drug and want it to unfold once it gets to its target protein. We need to study what the proper folding of the molecule is.”

Two more events were included in the programme. One was the mid-term meeting of the European Project CONNECT, involving 13 universities and focussed on geometric graphs. The last week the Programme hosted the 5th Austrian Japanese Mexican Spanish Workshop on Discrete Geometry. In both cases, people gathered in to discuss open problems of the field.

The feedback Vera and Rodrigo received for the whole programme was very positive. Vera and Rodrigo believe the quality of the course was especially high, and the lectures will be published for future use. “Networking has been very powerful,” says Rodrigo. “there are not many events in these fields like this. The atmosphere was so relaxed that sharing came very spontaneously. A student even gave salsa classes, a lecturer gave squash classes: this proves that people are establishing long-lasting bonds, that will probably accompany them throughout their careers.”

Participants

Professor of Computational Geometry

UPC

Ramón y Cajal Researcher

UPC

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]]>The post Meet the algebraic topologist who helps biologists to analyse the brain appeared first on BGSMath.

]]>Meet the algebraic topologist who helps biologists to analyse the brain

Three moments of Kathryn Hess’ Colloquim in Barcelona, at the Centre de Recerca Matemàtica (CRM); the last three images were presented by Prof. Hess during her presentation and are provided by the Blue Brain Project.

As many other brilliant mathematicians, US-born Kathryn Hess began her career very young. She graduated with a PhD from MIT when she was only 21. She then worked as a postdoc at the University of Stockholm, Nice, Toronto, and finally landed at the EPFL in 1999, where she holds the position of Associate Professor of Mathematics and Life Science since 2015. She is convinced that “biology needs all kinds of mathematics”. She says that, in her experience, “a lot of biologists have been very open to dialogue with mathematicians. They need help, their background in math is often not strong, but if mathematicians are willing to make an effort to understand their needs, they are very happy to collaborate”.

**Tell us something about the Blue Brain Project.**

The objective of the project is to reconstruct digitally and simulate activity in the brain of a rat, and ultimately the human brain. The human brain is formed by hundreds of billions of neurons and hundreds of trillions of synapses, through which electrical currents flow. The rat brain is smaller (2g vs 1.2 kg), but the structure is still complex, and its neocortex is similar. It has hundreds of millions of neurons and hundreds of billions of synapses! It’s like a “warm up” exercise for the human brain, but it’s still too much data to collect. So, we need to make a few well-chosen measurements to construct a model of the brain. The building blocks of the model are of course the neurons, the processing units of the brain. They come in different forms and shapes – there are 55 morphological types in our model! We use supercomputing to construct and simulate activity in this model, and we exploit the interconnections between biological experimental data. This way, we can produce models of the brain with very fine biological detail. The goal is to design a computer model of the rat’s neocortex as biologically accurate as possible in order to analyse its structure and functions.

**What’s mathematics’ contribution to the project?**

I entitled my talk “topological vistas” because I explore the many ways topology can be applied to neuroscience. For example, we examine neural activity through the filter of algebraic topology. It is normally difficult to see patterns in the firing of the neurons, but if we analyse the neural activity with the goggles of algebraic topology, we can see the mathematical signature of seemingly chaotic behaviour in the evolution of the firings with time. Algebraic topology describes the encoding process and perhaps will be able to visualize the moment the brain is making a decision. If we apply it to the “reconstructed neocortex”, the digital reconstruction of a 14-day old rat brain that was obtained in 2015, we can provide a description of its structure and function.

We make an abstract representation of circuits of neurons and how they connect together. We represent a neuron with a dot, and a connection with a segment. An arrow indicates a flow. We then construct “directed simplices” that represent families of neurons working together. The higher the “dimension” (a geometric representation of the structure in the neural network) of the simplices, the higher the coordination of the signal. We find that we have up to 8 neurons working together to amplify a signal. As you can see, algebraic topology has given us the tools to discern the inner structures in the brain and its functions.

**Why is algebraic topology so useful for this kind of problems? **

Applying graph theory to the analysis of the connectome (the map of neural connections in the brain) has already proved very useful in the past. This is not surprising for mathematicians, but perhaps it was a bit for neuroscientists. Algebraic topology is designed for the study of the notion of proximity and connectivity and of the emergence of global structure from local constraints. Furthermore, information usually flows in one direction in the brain, it cannot go backwards – the connections between neuron have a sense of direction imposed by the chemistry of the synapses. A perfect scenario to be tackled with algebraic topology.

**Sometimes you say that “the brain is made up of ‘multi-dimensional geometrical structures”. This may sound a bit puzzling to the lay person. What do you mean?**

People are often scared by the word “dimension”. It is just a way to say how big structures are. There are families of neurons working together to transmit messages further; the dimension is just the number of neurons working together (minus 1). If you represent these families geometrically, those are the dimensions that arise. The building blocks of the brain – i.e. the families of neurons – are put together in different ways. It’s like when you build a castle: how many windows and room does it have? In a topological space, we use something called Betti numbers: they count the cavities and loops arising from the way the neurons are connected together.

**How can we be sure that algebraic topology is not an oversimplification of a biological complex phenomenon?**

Because it reveals interesting information. One example is the functional role of simplices. The larger the group of neurons working together, the more highly correlated it is. Algebraic topology is able to quantify this. By using this mathematical filter, we can also manage to detect patterns in the way information flows through the brain that would be invisible otherwise.

**How is the collaboration between mathematicians and biologists? **

If there’s a good dialogue, it is easy to converge towards a model that works well. I have talked with a lot of biologists over the years, and it has always been easy to work together to set up good models. I, as a mathematician, have my own tool box, which does not always contain the right tools, though. The important message is that biology needs all kinds of mathematics. In my experience, a lot of biologists are looking for help. Their background in math is not always strong, but if mathematicians are willing to make an effort to understand their needs, they are very happy to work together with us.

**What’s the next challenge you want to face?**

Plasticity! We are studying what happens when some synapses become stronger, others weaker. One needs complex mathematical models for this – computation on grand scales. The Blue Brain Project is currently running plasticity simulations on a very powerful supercomputer at Argonne National Laboratory in the US, repeat patterns of stimuli, starting with a random distribution of strengths of synapses. After a while, neurons develop a preference for certain stimuli. We need more sophisticated topological tools for this analysis, since so far we have taken into account only whether there is a connection or not. In the future we intend to take into account the evolution of the weights of the synapses.

**You attended a special program for talented children. Would you recommend it?**

Not only would I recommend it full-heartedly, but I even created one at EPFL, called the Euler Course. It is open to any French-speaking child. We have an entrance exam, students taking it span from 9 to 13-years old. It’s a multiple-choice exam, and they are not familiar with most of the themes covered, so they have to work backwards from the possible answers. We also interview the children who do well on the exam together with their parents: we want truly motivated children, not those who are only pushed by their parents. We have approximately 25 students per class, and we simply replace their regular math course. Class is once per week for 3 hours in Lausanne and consists of lectures and exercises. The idea is that the first three years they just work through the regular school math programme, twice as fast, more in depth and more rigorously. After they finish school math, they begin university-level math. This way, those who want to do math at university can directly move to the second year; the others will just skip their math courses. It’s an incredible experience for them. Many are bored in school. With us, they learn how to think and how to structure their thought. Lots of them had never really studied before because it was too easy for them in school. They make good friends with people like them, hungry for knowledge just as they are. It replaces public schools, so we only charge a nominal fee of 100 francs per year, the rest is covered by EPFL and generous donors. For us it was extremely important that it was not just for children who could afford it.

**You are a role model for many young female scientists. How is life for a woman in the mathematical world? **

There were very few female role models when I was a child, few enough that I remember all of them. One was when I was in the accelerated programme myself. One day, a woman gave the only real math lecture about non-Euclidian geometry. It was exciting for me to discover that you could change the rules and the axioms and still get a functioning geometry! The most exciting thing I had ever heard was taught to me by a woman. Another one was at the university. At the time, I wanted to become an astrophysicist, so I took a lot of physics courses. One day, the teacher of my electromagnetism course, the only woman I ever had as a professor, told me: “you are doing very well in my course because you are a very good mathematician. But you have no physical intuition”. I was relieved – because being a physicist wasn’t coming naturally to me. She said something important to me at a crucial time of my life. Today, we are still too few women – and yes, I believe visibility is crucial for us!

Participants

Two videos describing Prof Hess’ research. The top one is from EPFL, the bottom one is a TED talk.

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]]>Fracking and fluid-induced microseismicity: a toll for our energy thirst?

During the last decades, we have witnessed an unprecedented increase in earthquakes related to human activities. Most of them involve the injection of highly pressurized fluids into deep layers within the Earth’s crust, in a quest to squeeze our almost-depleted hydrocarbon reserves or to harness the power of geothermal heat. As a paradigmatic example__, the number of earthquakes in the state of Oklahoma has increased by a factor of five between 2000 and 2012__ and by __almost 300 by 2015,__ to become the most seismically active region in the USA. This increase in seismic activity seems to be related to the massive increase in the number of operations of stimulation of gas and hydrocarbon reservoir through hydraulic fracturing, or ‘fracking’, and the underground disposal of its residual wastewater. The artificial enhancement of geothermal systems (also called EGS) provides an energy source much more sustainable than fossil fuels, but also relies on the injection of fluids to deep layers of the Earth crust. The problem is that EGS can also activate dormant faults and trigger strong earthquakes. This happened in the case of the 5.5-magnitude earthquake that struck Pohang, a densely populated region of South Korea on 15 November 2017. The seismic event and its aftershocks, causing $52 million in damage, __were allegedly triggered by a state-of-the-art EGS operation__. Other human activities involving injection of fluids have also been related to seismic activity. A local example of this phenomenon is the __alarming earthquake swarm activated offshore Tarragona and Castelló, in September and October 2013__, during the preliminary tests of the Castor project using a depleted natural gas reservoir for storage. The concern about this problem is growing worldwide, and collaborations between research institutions, public and private companies and policy makers are sprouting worldwide. We all have a clear goal: to understand, predict and prevent anthropogenic fluid-induced seismicity. Projects such as __GEISER__ in the EU, __SCITS__ in the USA, the __RING-GOCAD Consortium__ in France or the __MIC__ in Canada are good examples of these collaborations.

Industry partners are usually able to provide detailed geomechanical data of actual reservoirs and share the injection protocols used during their operations. Interdisciplinary research teams formed by geophysicists, seismologists, engineers, physicist and applied mathematicians use this data to develop and improve mathematical models of fluid-induced microseismicity based on their knowledge on fluid and wave propagation, material and fault mechanics and poromechanics.

The models are tested against the available seismic information of the area and catalogues obtained through *ad**-hoc* seismometer and geophone arrays active during and way after the operation. The overall research effort is used to design new hazard assessment techniques and protocols for risk mitigation that are proposed to policy makers.

Part of my current research is in collaboration with several labs in the University of Calgary associated to the MIC of Canada. As I have explained, human-induced activities are indeed capable of activating tectonic faults. But statistics can give us a hand to distinguish between fluid-induced microseismicity and tectonically activated seismicity. I am now studying the statistics and spatio-temporal correlations in microseismic catalogs, and the development of a stochastic model for fluid-induced microseismicity. Our model links together different conceptual paradigms in fracture modelling, such as percolation, fluid diffusion and stick-slip mechanics (the spontaneous jerking motion that can occur while two objects are sliding over each other). Our final goal is to understand how the fundamental features in the geomechanics determine the statistical laws of the microseismic catalogs.

Our hope is that, through our joint efforts, in the future we will be able to detect, predict and prevent the seismic hazard related to human activities, minimize risks and ascert responsibilities in the eventual case of damages and losses. Thanks to our research, fluid-induced microseismicity might, one day, be excluded from the long list of unavoidable tolls and consequences of our thirst for energy and scarce resources. *(Jordi Baró i Urbea)*

Participants

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]]>The post Maryna Viazovska, the Ucranian mathematician who could have won the Fields Medal (and still could) appeared first on BGSMath.

]]>**Maryna Viazovska, the Ucranian mathematician who could have won the Fields Medal (and still could)**

* Café con teoremas *section in* El País *about Maryna Viazovska, a Ucranian mathematician who, in 2016, solved the sphere-packing problem in dimension 24. According to Miranda, she could have been one of the 2018 Field Medalists, bringing the total number of women awarded with the distinction to two.

This year’s International Congress of Mathematicians (ICM), writes Eva Miranda, brought with it several surprises. One of them was not really new: no woman obtained the precious recognition. Many believed that Maryna Viazovska could have become the second woman to receive it, after Maryam Mirzakhani won the award in 2014.

“Maryna Viazovska (Kiev, Ukraine, 1984) did not lack reasons to be among the favourites: she defended her doctoral thesis in 2013 at the University of Bonn (Germany) and is already a professor at the prestigious Federal Polytechnic University of Lausanne (Switzerland); in 2016 she solved a famous geometric problem about packing spheres, for dimension eight, and published it in the Annals of Mathematics, one of the most prestigious mathematics journals. A week later, she did it for dimension 24, in a joint work with other collaborators, also published in the same journal. The problem of packing spheres appears in crystallography, but also in the theory of information developed by Claude Shannon and in big data. We can imagine its simplest formulation when placing oranges in a fruit stand: what is the best way to do it, so that they occupy the least possible space? They are usually arranged in a pyramidal form, following a harmonic and symmetrical structure, and in fact this is the optimal way to order them. This is one of the arrangements with the highest density, that is, it leaves less gaps between the oranges. Demonstrating mathematically that this is true is not as simple as it may seem.”

But this is not the last opportunity for Viazovska, says Miranda. In Saint Petersburg in 2022, where the next ICM will be held, she will still be younger than 40 (one of the requirements to obtain the Medal), so she will still be eligible for the award.

Read the entire op/ed in *El País *(in Spanish).

Participants

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]]>The post BGSMath–BANCO DE SANTANDER POSTDOCTORAL CALL 2017 appeared first on BGSMath.

]]>The postdoctoral fellowship on **Probability, Statistics and/or Computer Science** has been awarded to the following candidate:

The call for the postdoctoral fellowship on **Dynamical Systems **has been finally declared void since all eligible candidates have already been appointed to another positions**.**

A new call will be opened soon.

Barcelona, 23 July 2018.

**DAVID MORIÑA SOLER**

PhD from UAB (2013)

“Nous models per a sèries temporals”

Currently: Postdoctoral research fellow, Catalan Institute of Oncology (ICO)

Host research group (starting Sept. 2018)

Advanced Statistical Modelling Group at UAB

Host Researcher: Pere Puig.

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