Physics and Mathematics

A mathematical model shows a global trend towards mutualism between species

Wed, 21 Dec 2022 08:48:47 +0100

There are various types of ecological interactions between species in ecosystems. One of the best known is predation (one species feeds from another, to put it simply), but there are other varieties, such as competition for resources, mutualism, commensalism, parasitism, etc. However, it is known that these are not permanent states, because there may be transitions between these interactions as a result of evolution. For example, a predation relationship between species may eventually become a mutualistic or symbiotic relationship between them during the course of evolution.

This new mathematical model makes it possible to study the type of transitions in ecological interactions. “One of the conclusions we have found is that there is a clear trend towards mutualism: ecological interactions can start in any way, but in the majority of cases they eventually lead to a mutualistic relationship”, says one of the researchers, José Antonio Cuesta Ruiz, professor in UC3M’s Mathematics Department, who recently published this work in the scientific journal Physical Review E together with researchers from UPM, Universidad Rey Juan Carlos de Madrid and Universidad del Pacífico at Lima (Peru).

In this article, they have also shown the high frequency with which these transitions occur in nature, discovering evolutionary trajectories that go through various intermediate states, according to the researchers: “Despite being a simple model, its emergent behavior is complex, it shows transitions between different ecological relationships, and is able to go through different stages of mutualism, predation and competition before reaching its final state”, add Javier Galeano and Juan Manuel Pastor, lecturers at UPM and co-authors of the work.

For their study, the researchers have used classical models of population dynamics, to which they have applied a standard technique in evolutionary theory, called adaptive dynamics. This technique allows them to find dynamic equations for the parameters of the population model, which determine the nature of ecological interactions, making it possible to study how these interactions change over time. “These types of models, despite being very simple, are able to capture essential elements to provide mechanisms of emergent phenomena. They are very useful when studying complex systems”, says Cuesta.

Bibliographic reference: Luciano Stucchi, Javier Galeano, Juan Manuel Pastor, Jose María Iriondo, José A. Cuesta (2022). Prevalence of mutualism in a simple model of microbial coevolution. Physical Review E. Vol. 106, Iss. 5. Published 1 November 2022.

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UC3M study finds a mathematical link between sociopolitical event and advanced cyberattacks

Thu, 27 Oct 2022 11:59:51 +0200

The cyberattacks analysed by these researchers are known as Advanced Persistent Threats (known as APTs). “Their complexity indicates that it is the States that are behind them”, explains one of the study’s authors, Lorena González Manzano, lecturer at the Computer Security Lab in UC3M’s Computer Science Department. In this research they have analysed whether there is a relationship between cyberattacks and certain strategic, economic and military events.

Although there was some attribution of intention of these APTs, until now there wasn’t a mathematical link that would allow these attacks to be modelled. However, this work led by lecturer González and published in the Security and Communication Networks journal indicates that it is possible to establish this link. “The model is based on information published by the media and other economic indicators to explain the occurrence of APTs”, says another of the study’s authors, lecturer José María de Fuentes, from the same UC3M research group. The motivations for these cyberattacks are very varied. “They are much more sophisticated than those that can affect normal users. They are usually aimed at intellectual property theft or espionage”, says Lorena González Manzano.

This research opens the door to future lines of work, such as “the prediction of cyberattacks through the observation of other variables which have nothing to do with the cyber world”, according to de Fuentes. "For example, in some cases the data on the level of exports (such as mobile phones) is useful to determine if a cyber attack is likely to occur in a given country", adds lecturer González Manzano.

This work is interdisciplinary in nature and integrates “geopolitical factors (to understand the relationship between countries) with data on cyberattacks and combines all of this with a mathematical perspective”, explain the researchers. This has been possible thanks to the CAVTIONS-CM-UC3M project, co-funded by the Community of Madrid and UC3M and led by lecturer González together with lecturer FlorabelQuispe, from UC3M’s Department of Public International Law, Ecclesiastical Law and Philosophy of Law.

Bibliographic Reference: L González-Manzano, JM de Fuentes, C Ramos, Á Sánchez, F Quispe (2022). Identifying Key Relationships between Nation-State Cyberattacks and Geopolitical and Economic Factors: A Model. Security and Communication Networks, volume 2022, article ID 5784674, 11 pages. https://doi.org/10.1155/2022/5784674

The COIT Pioneras_IT 2022 Awards recognise UC3M

Thu, 20 Oct 2022 10:19:16 +0200

The aim of these awards, which were presented at an event held on the 19th of October, is to raise awareness of women’s contributions in the field of telecommunications. The Pioneras_IT Educational Institution Special Mention was received by UC3M’s Deputy Vice-Rector for Promotion, Celeste Campo Vázquez.

This special mention was given to UC3M for its STEM for Girls UC3M initiative, a programme to promote STEM (Science, Technology, Engineering, Mathematics) vocations among girls and young women and encompasses four fields of work: mentoring activities, competitions, technological workshops and performing arts. It has received funding from the FECYT and the Women’s Institute.

The Pioneras_IT Award was created in 2019 by the COIT Women’s IT working group with the aim of increasing the visibility of female talent in the technological field and, in particular, in the telecommunications field, traditionally dominated by men. By highlighting the professional careers of several female pioneers, it aims to stimulate scientific and technical vocations among girls and young women for the future.

Algorithm for predicting biological age has been developed

Mon, 10 Oct 2022 10:33:14 +0200

According to information provided by the Spanish National Institute of Statistics (INE, in its Spanish acronym), the ageing rate of the Spanish population rose from 0.908 in 1997 to 1.183 in 2017. In turn, life expectancy increased exponentially over the same period of time.

To obtain this data, the indicator which is commonly used is chronological age. However, the ageing of each person is also related to their lifestyle, among other factors.

The Aristóteles project, carried out by a UC3M research team, has developed a new methodology for the use of a more precise indicator when calculating real population ageing. The development consists of an algorithm which predicts people’s biological age by identifying factors that contribute to population ageing, and calculates the magnitude of the influence of each one.

“Ageing is progressive and very complex because each person ages differently. Some of the influential elements are modifiable, so using another type of indicator, such as biological age, gives us a tool that allows us to identify unhealthy factors in order to correct them and thus increase life expectancy”, says María Durbán, researcher in the Department of Statistics and project coordinator.

This predictive algorithm is the first to combine lifestyle and genetic and non-genetic biomarkers in the same model. Its main applications are in the medical and public health fields, as well as in business fields.

A mathematical model helps to explain how blood circulates in the brain

Wed, 02 Feb 2022 13:18:30 +0100

Flow networks are made up of a set of connections that carry fluid. The current that circulates through these “ducts” usually increases if the pressure difference between the inlet and outlet increases. However, in certain non-linear flow networks, such as the circulatory system, the current may fall as the pressure difference increases. “This behaviour is known as negative differential resistance and has been observed in blood vessels and devices that conduct electricity,” says one of the researchers, Miguel Ruiz García, a CONEX-Plus researcher at the UC3M’s Department of Mathematics.

Blood vessels are more like active organs than rigid ducts. Specifically, the arteries are covered by vascular musculature that allows them to contract or expand in response to different stimuli. For example, when a blood vessel that feeds an organ detects an increase in pressure at its inlet, it can respond to that increase in pressure by contracting (compressing its muscles) in order to reduce flow and protect the organ. “This effect is called the myogenic mechanism, and there are similar effects that cause the flow through a blood vessel, which is not a linear function of the pressure difference, but a non-linear function that sometimes has a negative differential resistance,” notes Miguel Ruiz García.

This theoretical model, which allows the size of the network to be estimated using a method that takes the connections between ducts into account and predicts the frequency of pressure oscillations, was recently presented at the International Conference on Complex Networks and their Applications. “We were able to observe interesting phenomena, such as the appearance of waves that travel through these complex networks. It turns out that the frequency of these oscillations changes as we change the structure of the network in very different ways. Explaining why these different structural changes lead to similar changes in frequency was very challenging and we were only able to do it using a topological metric: a value that measures the “effective” size of the network,” explains Miguel Ruiz García.

They are called topological metrics because they use the network’s topology, in other words, they take their internal connections into account. “We can measure, for example, the distance between cities in kilometres and say that Madrid is closer to Teruel than to Barcelona. However, if we measure the distance as 1 divided by the number of trains that travel from Madrid to each of these cities on a daily basis, then Barcelona is much “closer” than Teruel according to our new way of measuring. This type of measure provides us with information about the difficulty of travelling from one point to another within the network,” says the researcher. “Similarly, the topological measure we use tells us the effective size of the system, so if the system is smaller effectively then waves take less time to get from one end to another and their frequency increases. This is similar to the previous example, in which it is easier to get to Barcelona than Teruel,” he concludes.

“Our theoretical results could help other researchers better understand the oscillations that are observed in blood that circulates in our brain, as these blood vessels present the conditions that our model is studying,” says Miguel Ruiz García. “On the other hand,” he continues “we hope that our experimental work will develop new devices that help control flow in microfluidic devices (devices with very small pipes that are used in the pharmaceutical industry, as well as in many laboratory devices)”.

This piece of research began when Miguel Ruiz García was working as a post-doctoral researcher at the University of Pennsylvania (USA), along with lecturer Eleni Katifori. This research has been able to be developed thanks to his incorporation into the UC3M as a CONEX-Plus talent attraction programme researcher, funded by the University and the European Commission through the Marie Skłodowska-Curie COFUND Actions (GA 801538) from the European Horizon 2020 Framework Programme.

More information:

Ruiz-Garcia, M. Katifori, E. (2021). Topology controls the emergent dynamics in nonlinear flow networks. The 10th International Conference on Complex Networks and their Applications. November 30 - December 2.. Madrid, España. https://complexnetworks.org/

Ruiz-Garcia, M. Katifori, E. (2021). Emergent dynamics in excitable flow systems, Physical Review E 103 (6), 062301. https://doi.org/10.1103/PhysRevE.103.062301

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The influence collective risks have on the acceptance of social norms is being analysed

Wed, 13 Oct 2021 10:56:47 +0200

This article analyses the relationship between social norms and behaviour in collective risk situations. “Specifically, we have seen that the greater the risk of a collective catastrophe, the greater the strength of social norms (and, in particular, the punishment for those who do not comply with them is increased). However, we have also seen that as the perception of risk decreases, so does the monitoring and compliance with the norms,” explains one of the study’s authors, Anxo Sánchez from the Complex Systems Interdisciplinary Group (GISC, in its Spanish acronym) at the UC3M’s Department of Mathematics.

Therefore, in the context of climate change, “if people perceive it as an imminent risk, the social norm of saving energy on heating and/or air conditioning within households may increase, which would lead to lower emissions; however, as long as the perceived risk does not pose a threat, or decreases, these social norms are adhered to less,” note the authors of this paper, which was recently published in the Nature Communications journal.

Another case where the results of this study could be applied is the COVID pandemic. “Since the vaccinations have been implemented, society perceives the risk as being lower. This leads to two things that align with our study; on the one hand, in groups where there were not many people complying with the regulation of wearing a mask, such as among younger age groups, this norm has suddenly disappeared. On the other hand, however, older people continue to wear them outside, even when it is no longer compulsory to do so. In the case of the latter group, a habit has been formed due to previously strict mask wearing regulations (we should also consider the pressure exerted by those wearing masks on those who did not),” notes Anxo Sánchez.

In order to conduct their research, the scientists designed a social experiment consisting of 300 participants, who were split into groups of six. They were asked to make one decision every day for a month: they were asked to contribute a number of points (as if they were money) in order to prevent a catastrophe. If they did not “invest” enough, the catastrophe would strike and everyone would lose their points. They were then asked about their expectations in regard to what other participants would contribute and what others expected of them, which allowed scientists to identify the social norm and to study the behaviour of those who assimilated these cooperative norms.

This study is framed within the context of collective (or emergent) phenomena observed in complex systems, with a perspective inspired by physics. In this sense, each individual had their own expectations and norms, but modified them by observing others, and only when these expectations and norms were shared by many people did they become social norms.

More information:

Bibliography: Szekely, A., Lipari, F., Antonioni, A. et al. Evidence from a long-term experiment that collective risks change social norms and promote cooperation. Nat Commun 12, 5452 (2021). https://doi.org/10.1038/s41467-021-25734-w More info: https://www.nature.com/articles/s41467-021-25734-w

Mathematics to improve macular degeneration treatment

Mon, 14 Jun 2021 13:52:17 +0200

Age-related macular degeneration (AMD) is a degenerative disease of the macula, the central area of the retina. There is currently no cure for the disease and it is characterised by a gradual loss of central vision and is the leading cause of blindness in developed countries in people over the age of 65. It is estimated that AMD affects around 800,000 people in Spain. It is estimated that around 196 million people are affected worldwide and it is also estimated that this number will reach 288 million by 2040.

There are two types of AMD: the dry or atrophic phase, which is usually the first and most common phase which progresses slowly; the acute phase, known as the wet or exudative phase, which occurs less frequently but has a worse prognosis at a visual level. In this latter form of AMD, there is an angiogenesis under the retina, an abnormal growth of very fragile blood vessels that may lose fluid or bleed, which can knock off and destroy the photoreceptor cells needed to see.

In their research, scientists from the UC3M have created a computational model simulation of angiogenesis (the propagation of blood capillaries) that takes how this process occurs in the eye into account. “What happens in this case is that, with age, a barrier (called the Bruch’s membrane) that separates the capillary vessels from the inner part of the retina becomes less permeable and, therefore, does not deliver enough oxygen or nutrients to the photoreceptors. They then emit a signalling protein (called a vessel endothelial growth factor) that diffuses, passes to the blood vessels, and triggers this angiogenesis, which is what causes the disease,” explains Luis L. Bonilla from the UC3M’s “Gregorio MillánBarbany” University Institute for Modelling and Simulation in Fluid Dynamics, Nanoscience and Industrial Mathematics, who recently published a scientific article with Rocío Vega and Manuel Carretero in the Biomedicines journal.

In practice, relatively little is known about the evolution and appearance of this disease and researchers hope that using this mathematical modelling they will be able to better understand how this pathology is created, how long it takes to progress, and if there is a way to stop it using current therapies. “The model has several parameters that characterise the progression of the disease. One can change them and predict how the disease will progress according to values, so it can be used to control how the process happens,” explains Professor Bonilla.

Numerical simulations of the model suggest that therapies based on decreasing growth factors and proteins that are crucial in angiogenesis may temporarily slow the disease down, while other therapies based on improving cell adhesion may be more effective in the long term. In addition to this, this model could be used to research other retinal diseases, scientists say, such as diabetic retinopathy or that associated with premature babies, as, in these cases, these diseases also occur due to abnormal blood vessel growth.

Bibliography: R. Vega, M. Carretero, L. L. Bonilla, Anomalous Angiogenesis in Retina. Biomedicines 9, 224 (2021) (21 pp). doi:10.3390/biomedicines9020224

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La UC3M clausura el Technovation Girls 2021

Thu, 10 Jun 2021 09:05:27 +0200

Technovation Girls es un proyecto internacional que tiene como objetivo acercar la ciencia y la innovación a chicas entre 10 y 18 años. Es un programa de Iridescent, una organización global de tecnología e ingeniería sin ánimo de lucro, y constituye la mayor competición de emprendimiento tecnológico para niñas. El objetivo es fomentar la innovación y la creatividad, así como reducir la brecha de género existente en las carreras STEM (Ciencia, Tecnología, Ingeniería y Matemáticas).

Cada año, se reta a grupos de un máximo de cinco niñas a desarrollar un plan de negocio y una aplicación móvil para solucionar un problema de su comunidad y dar respuesta a una necesidad social relacionada con las áreas de educación, igualdad, medioambiente, salud, paz o pobreza. Este año, a pesar de las complicaciones, las jóvenes y sus mentores han conseguido sacar adelante sus proyectos. Este evento que organiza la UC3M está pensado para que los equipos puedan exponer sus proyectos y el público asistente de forma virtual pueda intervenir y preguntar en directo por las aplicaciones y su desarrollo.

La bienvenida de esta jornada virtual correrá a cargo de la vicerrectora de Estudiantes e Igualdad de la UC3M, Mónica Campos. A continuación participará la responsable del Programa STEM for Girls UC3M, Celeste Campo, vicerrectora adjunta de Promoción de la Universidad. Posteriormente intervendrán los cinco equipos semifinalistas a nivel mundial en las categorías senior y junior. Después participará la General Manager of Europe at CoverWallet, an Aon Company, Elena Gonzalez-Blanco García. Clausurará el evento Alicia Mancheño, de Power to Code, embajadores regionales de Technovation Girls.

La Universidad integra esta actividad en su programa STEM for Girls UC3M de fomento de vocaciones tecnológicas y científicas, dirigido a niñas y jóvenes de secundaria y bachillerato. Este programa se ha desarrollado a lo largo del curso 2020/21 en cuatro ámbitos de trabajo: actividades de mentoring, competiciones, talleres tecnológicos y artes escénicas. Esta actividad, además, cuenta con apoyo del Ministerio de Igualdad a través de la Convocatoria anual que realiza el Instituto de las Mujeres.

Esta jornada se podrá seguir a través del canal de YouTube de la UC3M: https://www.youtube.com/watch?v=0xcf9xmesVA

Este año los equipos participantes podrán exponer sus apps en una feria virtual que se desarrollará del 11 al 13 de junio, en la que intervendrá con una ponencia Sara Guerrero, profesora del departamento de Bioingeniería de la UC3M. Enlace Feria Technovation Girls.

Más información: Web del evento Technovation Girls 2021

The factors that improve job resiliency in North American cities have been identified

Tue, 27 Apr 2021 11:18:54 +0200

Knowing and understanding which factors contribute to the health of job markets is interesting as it can help promote faster recovery after a crisis, such as a major economic recession or the current COVID pandemic. Traditional studies perceive the worker as someone linked to a specific job in a sector. However, in the real-world professionals often end up working in other sectors that require similar skills. In this sense, researchers consider job markets as being something similar to ecosystems, where organisms are linked in a complex network of interactions.

In this context, an effective job market depends on many aspects, such as diversity and the number of job offers or training opportunities that workers have in order to acquire new skills, for example. In this scientific study, researchers have found that cities where all of these factors are very similar respond differently in regard to recovering from an economic crisis. Why? “We have discovered that the difference comes, in part, from the jobs ‘map’, a network that tells us how jobs within a city are related, according to the similarity of the skills required to perform those jobs,” explains Esteban Moro, an associate professor at the UC3M’s Department of Mathematics and co-author of the study, who is currently a visiting professor at the MIT Media Lab.

“When that map is extremely limited, in other words, when there is very little chance of finding another similar job (what we call “job connectivity”), cities are less prepared for a job crisis. In contrast, when that map offers lots of possibilities of moving from one job to another similar one, the city is better prepared. It also has an effect on workers’ wages: workers in cities that have a more diverse network earn more than those in the same occupation in cities where this network is more limited,” adds Esteban Moro.

Ecology, complex networks and job connectivity

In ecology and other domains where complex networks are present, resilience has been closely linked to the “connectivity” of the networks. In nature, for example, ecosystems with lots of connections have proven to be more resistant to certain shocks (such as changes in acidity or temperature) than those with fewer connections. Inspired by this idea and drawing on previous network modelling research, the authors of the study modelled the relationships between jobs in several cities across the United States. Just as connectivity in nature fosters resilience, they predicted that cities with jobs connected by overlapping skills and geography would fare better in the face of economic shock than those without such networks.

In order to validate this, the researchers examined data from the Bureau of Labor Statistics for all metropolitan areas in the US from the beginning to the end of the Great Recession (2008-2014). Based on this data, they created maps of the job landscape in each area, including the number of specific jobs, their geographical distribution, and the extent to which the skills they required overlapped with other jobs in the area. The size of a given city, as well as its employment diversity, played a role in resilience, with bigger, more diverse cities obtaining better results than smaller and less-diverse ones. However, by controlling size and diversity and taking job connectivity into account, predictions of peak unemployment rates during the recession improved significantly. In other words, cities where job connectivity was higher before the crash were significantly more resilient and recovered faster than those with less-connected markets.

Even in the absence of temporary crises like the Great Recession or the COVID pandemic, phenomena, such as automation, might radically change the job landscape in many areas in the coming years. How can cities prepare for this disruption? The researchers in this study extended their model to predict how job markets would behave when facing job loss due to automation. They found that while cities of similar sizes would be affected similarly in the early stages of automation shocks, those with well-connected job networks would provide better opportunities for displaced workers to find other jobs. This prevents widespread unemployment and, in some cases, even leads to more jobs being created as a result of the initial automation shock.

The findings of this study suggest that policymakers should consider job connectivity when planning for the future of employment in their regions, especially where automation is expected to replace a large number of jobs. Furthermore, increased connectivity does not just result in lower unemployment, it also contributes to a rise in overall wages. These results provide a new perspective on discussions about the future of employment and may help guide and complement current decisions about where to invest in job creation and training programmes, say researchers.

Bibliography: Moro, E., Frank, M.R., Pentland, A. et al. Universal resilience patterns in labor markets. Nat Commun 12, 1972 (2021). https://doi.org/10.1038/s41467-021-22086-3

UC3M research examines how to improve the measurement of the surface viscosity of filaments and membranes

Wed, 17 Mar 2021 09:27:19 +0100

Liquid filaments can be found in various contexts in our everyday lives, such as a stream of tap water, shower gel or the milk we put in our coffees. On a biological level, they are present in processes that occur inside organisms, "such as in the stretching and breakup of vesicles, in cell division or in the protein-covered filaments within cells, among others. In addition to this, they are crucial in a multitude of technologies where the precise control of drop production is required, such as in 3D printing and the additive manufacturing, for example.

These liquid filaments are inherently unstable due to their surface tension, resulting in a process in which small disturbances are amplified causing the drops to fragment. This can be seen in saliva filaments, for example, that form on our lips and eventually end up being expelled in the form of droplets during speech, or in the water stream in showers which “breaks” when it is very narrow and ends up forming small droplets. “This is because spheres are the geometric shape with the smallest surface for a fixed given volume, so adopting a spherical shape minimises surface energy”, explain Alejandro Martínez Calvo and Alejandro Sevilla Santiago from the UC3M’s Fluid Mechanics Group.

In their research, recently published in the Physical Review Letters journal, they have theoretically and numerically studied a case in which the filament surface is viscous, which occurs when the surface is covered by a concentration of molecules (usually called surfactants). In some cases, these types of molecules are able to form a complex structure that gives the surface some resistance to flow, which manifests itself through surface viscosity.

The measurement of the coefficient of surface viscosity of liquid filaments and biological membranes consisting of these molecules is a challenge at the moment, due to the physiochemical complexity associated with hydrodynamic coupling of the filament’s surface with its interior. In their work, the scientists have discovered a new universal framework where the surface tension is in dynamic equilibrium with the surface viscous force, resulting in an exponential thinning of the filament radius until it ends up taking the form of drops of spherical vesicles, with a time decay that depends only on the surface properties, among which is the surface viscosity.

This work would be a significant step for the development of a non-intrusive method of measurement of viscosity coefficients which would have a greater accuracy than those currently available. Current methods of measurement make use of moving mechanical parts that distort the interface, such as cones, plates, cylinders, or rings that are placed on the surface and moved around in a controlled manner. These intrusive methods create variations in molecule concentration that give rise to surface elastic forces, in addition to their own surface viscose forces that are intended to be measured. “In this configuration we have studied, the distortion of the interface is not caused from the outside of the system through mechanical methods but occurs spontaneously. Thus, the measurement technique that could be developed with our idea would be non-intrusive, as measuring the rate at which the filament is distorted using photographic techniques would be sufficient”, state the researchers.

Bibliography: Martínez-Calvo, A. Sevilla, A. (2020). Universal Thinning of Liquid Filaments under Dominant Surface Forces. Phys. Rev. Lett. 125, 114502 https://doi.org/10.1103/PhysRevLett.125.114502

UC3M researchers analyse the Spanish population’s public spending preferences

Fri, 29 Jan 2021 10:42:40 +0100

The project makes it possible to understand which spending areas the Spanish population would like to guide the public budget: health service is the top priority for the Spanish public, followed by education. Other items have been grouped together, starting with pensions and R&D&I, culture and environment, infrastructure, and defence and security.

This project was carried out during the final quarter of 2020, in the midst of the COVID-19 health crisis and its very present economic and social consequences, therefore, it will be interesting to compare whether these results will be maintained once the pandemic has passed, according to the authors of the paper.

The UC3M researchers involved in this project are Antonio Cabrales, professor in the Department of Economics, and Anxo Sánchez, professor in the Department of Mathematics. “The study was triggered by the need to understand the population’s real preferences in regard to public expenditure. This isn’t an easy feat. For example, if you think about how many people say their favourite television programmes are the documentaries on La 2. When you compare this data with actual viewing figures, you realise that this isn’t the case. Surveys are needed that are compatible with people’s real motivations and take the cognitive complexity of the task into account,” says Antonio Cabrales.

An innovative methodology was used to carry out this project, combining a demoscopic survey (on a large representative sample of the Spanish population) with an economically motivated experiment using behavioural economic techniques. The results show a very high level of consistency between what the public say when asked for their opinion and what they do in an experiment that they can earn money from.

“The experiment motivated by economic gain confirms the results of surveys conducted using standard methodology, but it also provides interesting results that the surveys did not highlight,” notes Anxo Sánchez.

A mathematical study describes how metastasis starts

Mon, 18 Jan 2021 10:07:20 +0100

This research analyses the collective movement of cells in tissues, a process that, in addition to being essential in pathological developments, such as tumor invasion and metastasis, plays a central role in physiological processes, such as wound healing, embryonic development or tissue reconstruction, for example. In order to unravel the complexity of these processes, some previous scientific studies have carried out various experiments that seek to ascertain the role of certain chemical, mechanical and biological factors.

In this work, published in PLoS Computational Biology, researchers from the UC3M and UCM have now used a combination of mathematical modelling, numerical simulations and a topological analysis of data extracted from simulations and experiments in order to understand how cancer cells invade healthy cells. “A simplification of the early stages of cancerous metastasis is that tumor cells move as a collective and displace a group of normal cells in healthy tissue,” explain the paper’s authors, Luis L. Bonilla and Carolina Trenado, from the UC3M Department of Mathematics, and Ana Carpio, from the UCM Department of Applied Mathematics.

“By selecting the right cell groups and using an appropriate software and cellular dynamics, we have been able to simulate the way in which cancerous cells invade healthy tissue,” the scientists note. In order to carry out this simulation, they have used data from previous experiments and a Voronoi diagram (named after the Russian mathematician Gregory Voronoi) to conduct an irregular tessellation in which cells are polygons that do not overlap and have no spaces between them. In the model, the centers of cells are subject to forces of a different origin, the researchers explain, some maintain tessellation and optimize the area and perimeter, others are inertial forces of biological origin, and there are active forces aligning the speeds of neighboring cells, as well as friction and noise.

In order to automatically track the progression of the barrier or boundary between cancerous and normal cells, researchers have used topological data analysis techniques, which are being used for the first time in this type of study. “Based on a series of successive images from experiments, as well as numerical simulations, topological changes in the interfaces have been grouped, plotted, and classified automatically as the cancer cells progress,” note the scientists.

The techniques developed within the framework of this study can be scaled up to a larger volume of data, if these studies were to be carried out on a larger scale. In addition to this, these same techniques may be relevant in the field of tissue bioengineering to study how the biophysical characteristics of different materials affect organ and tissue regeneration.

Bibliography: Bonilla LL, Carpio A, Trenado C (2020) Tracking collective cell motion by topological data analysis. PLoSComput Biol 16(12): e1008407.https://doi.org/10.1371/journal.pcbi.1008407

Big Data will analyse the mystery of Beethoven’s metronome

Thu, 17 Dec 2020 08:49:43 +0100

Ludwig van Beethoven (1770-1827) was one of the first composers to start using a metronome, a device patented by Johann Nepomuk Maelzel in 1815. At that time, he started to edit his works with numerical marks with metronome indications. Doubts about the validity of these marks date back to the 19th century and during the 20th century many musicological analyses were carried out, some of which already pointed to the hypothesis that the metronome was broken, an assumption that could never be verified. In any case, most orchestra conductors have omitted these marks as they consider them to be too fast (Romanticism), whereas since the 1980s, other conductors (Historicism) have used them to play Beethoven. However, music critics and the public described these concerts as frantic and even unpleasant.

Previous scientific research, such as Sture Forsén’s study in 2013, has pointed to several defects that may have affected the metronome, causing it to function slower, which would have led the composer from Bonn to choose faster marks than those actually proposed. In order to validate this explanation, researchers from the UC3M and UNED have systematically compared the metronomic marks with contemporary interpretations. This requires physical skills to model the metronome mathematically, analyse data, computing, usability, and, of course, music skills. Overall, they have analysed the tempo and its variations for each movement of 36 symphonies interpreted by 36 different conductors, a total of 169 hours of music.

“Our study has revealed that conductors tend to play slower than Beethoven indicated. Even those who aim to follow his directions to the letter! The tempi indicated by the composer are, in general, too fast, to the point that, collectively, musicians tend to slow them down,” says Iñaki Ucar, one of the authors of this research, data scientist at the UC3M’s Big Data Institute, and clarinetist. This slowing down follows, on average, a systematic deviation, so it is not random, but conductors tend to play consistently below Beethoven's marks. “This deviation could be explained by the composer reading the scale of the apparatus in the wrong place, for example, under the weight instead of above. Ultimately, this would be a problem caused by using new technology,” says Almudena Martín Castro, the other author of the study, user experience designer and pianist, who carried out this research within the framework of her Bachelor Thesis for her Degree in Physics at UNED.

In this study, researchers have developed a mathematical model for the metronome based on a double pendulum, perfected with three types of corrections which take the amplitude of its oscillation, the friction of its mechanism, the impulse force, and the mass of its rod, an aspect that had not been considered in previous work, into account. “With the help of this model, we developed a methodology for estimating the original parameters of Beethoven’s metronome from photographs that are available and the patent outline,” the work explains. In addition to this, they dismantled a modern metronome to measure it and use it to validate both the mathematical model and methodology.

The researchers tried to identify a “break” in the metronome that gave rise to the slow tempi usually followed by musicians. They tried to change the metronome’s mass (it may have been damaged and a piece may have fallen off), move it onto the rod, increase the friction (the metronome may have been poorly lubricated) and even testing the assumption that the apparatus may have been misplaced, leaning over the piano while the composer was creating his music. “None of the hypotheses matched what the data told us, which is a homogeneous slowdown in the tempi on the entire scale. Finally, we considered the fact that the deviation matches the size of the metronome’s weight exactly, and we also found the annotation ‘108 or 120’ on the first page of the manuscript for his ninth symphony, which indicates that the composer doubted where he was reading at least once. Suddenly, it all made sense: Beethoven was able to write down a lot of these marks by reading the tempo in the wrong place,” they explain.

This methodology could be applied when investigating the work of other classical composers, as they are able to extract the tempo from a musical recording and clean up the data so they can be compared. “Studying the relationship between the tempo played and marks from other composers would be very interesting, or even looking for the ‘correct tempo’ for composers who did not leave any metronomic marks. Is it possible that there is an average tempo at which people usually interpret Bach's fugues, for example?” they ask.

More information:

Bibliography: Martín-Castro, Almudena; Ucar, Iñaki (2020). Conductors’ tempo choices shed light over Beethoven’s metronome. PLOS ONE. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0243616

The UC3M is awarded for its STEM for Girls educational programme

Fri, 30 Oct 2020 13:23:10 +0100

The UC3M won the award for its STEM4GirlsUC3M initiative, a programme that promotes STEM (Science, Technology, Engineering, Mathematics) careers among girls and young women. The initiative responds to the drop in the number of students choosing technical degree courses in recent years, with this drop being more pronounced among women. The University competed in the "Best company in STEM education" category, which also included BP and Johnson & Johnson.

STEM4GirlsUC3M is a programme aimed at promotingtechnological and scientific careersamong girls and young women in secondary level education. It has been running since the 2018/2019 academic year with the implementation of various technological workshops, a mentoring programme, the exchange of experiences between researchers and students and a performing arts project. This activity is also supported by the Spanish Foundation for Science and Technology (FECYT in the Spanish acronym) of the Spanish Ministry of Science and Innovation, and the Institute of Women and Equal Opportunities.

The awards ceremony was held digitally and was inaugurated by Ruth Pindado, Director General for Women inthe Castilla y León Regional Government. During her address, she welcomed the creation of these awards, which will provide "greater social recognition for the integration of our young women into what are known as the STEM disciplines".

The judging panel for this first edition of the STEM Talent Girl Awards was made up of experts and executives in the technology sector, such as Isabel Blanco, Minister for Family and Equal Opportunities in the Castilla y León Regional Government; Javier Rodríguez Zapatero, Chairman of ISDI; Elena Díaz-Alejo, Manager of Corporate Citizenship and Institutional Relations at Samsung; Alberto Gómez Barahona, President of the Universidad Isabel I; José María de la Torre, Managing Director Southern Europe, Chairman and Board Member of Hewlett Packard Enterprise; Cristina Vall-Losada, Head of Global Corporate Communications; David Calle, CEO & Founder of BeUnicoos; and María Jesús Prieto, a telecommunications engineer from the Universidad Politécnica de Madrid.

More information at: https://talent-girl.com/stg-awards/

The UC3M is amongst the best universities worldwide in seven academic fields

Wed, 28 Oct 2020 12:42:13 +0100

In the area of Law, the UC3M is amongst the 200 best institutions worldwide, according to WSR 2021 Law of the THE. In the field of Business Administration and Management, Accounting, Finances, Economics and Econometrics, the UC3M is amongst the 300 best international universities, according to the WSR 2021 Business and Economics of the THE.

In Arts and Humanities, the UC3M is ranked amongst the 400 best universities on an international level, according to WSR 2021 Arts and Humanities of the THE, while it ranks in the top 500 for Computer Science, according to the WSR 2021 Computer Science.

The University also holds notable positions in Social Sciences (WSR 2021 Social Sciences) and Engineering (WSR 2021 Engineering), being placed within the top 600 worldwide. In addition, the UC3M also holds an outstanding position worldwide (in the Top 800) in Physical Sciences, according to WSR 2021 Physical Sciences.

This classification by subject uses the same methodology as the THE’s World University Rankings. To do this, they analyse thirteen performance indicators in five important fields: teaching, research, scientific reunions, international impact, and the university’s relationship with industry. The methodology has been recalibrated to adapt to the different academic fields analysed.

More information: THE Ranking by Subject 2021 Website

Research carried out analyses how 3D printed metals fracture

Tue, 22 Sep 2020 10:11:34 +0200

3D printed metals have been used since the 1980s to produce a wide range of parts for various industries. These materials often have tiny pores inside them (around dozens of micrometres in size), which can get bigger when a load is applied to them, due to their manufacturing process. The team of researchers has analysed what happens to these “micro voids” when applying a load to them in order to understand how these ductile metals (capable of absorbing energy) fracture.

“For example, most of the structural elements in cars are made of ductile metal, so that they are able to absorb energy in the event of a collision. This means that security will be increased if a traffic accident occurs. So, understanding and predicting how ductile metals fracture is equal to optimising the design of energy absorbing structures in impacts in critical industrial sectors,” explains one of the study’s authors, Guadalupe Vadillo from the Nonlinear Solid Mechanics research team in the UC3M’s Department of Continuum Mechanics and Structural Analysis.

Her piece of work was recently published in the International Journal of Plasticity and has identified two mechanisms which cause the failure of the material. Firstly, the appearance and growth of micro pores which cause the material to soften until it breaks, and secondly, coalescence, which occurs when several micro pores within the material join and interact with each other, accelerating the fracture.

“During this work, we have identified how the micro voids or intrinsic micro pores in the material grow, shrink and interact with each other by accelerating or delaying the fracture of this material, depending on the viscosity of the material (how quickly it deforms when a load is applied), the speed at which the load is applied to the material and the loading path (direction and other factors),” Guadalupe Vadillo summarises.

Advances in this field improve our understanding of how 3D printed ductile metals behave and will help us design and manufacture sturdier parts and components in a variety of industries. These materials can be used in processes where energy absorption is important, such as in the manufacture of new fuselages in the aerospace industry, different car parts in the automotive industry or for developing implants in the biomedical industry.

This research is part of the QUANTIFY project, a Marie Skłodowska-Curie Research and Innovation Staff Exchange (RISE) Action which was created to promote training and research placements among academic staff from different institutions around the world. This European research project, which is part of the Horizon 2020 programme (GA777896) is being led by the UC3M and 8 institutions (4 European and 4 American) are taking part in order to share knowledge to understand the effect of anisotropy and porosity on the breakdown of lightweight structures.

Bibliography: Reboul, J. Ankit Srivastava, A. Osovski, S. Vadillo, G. (2020). Influence of strain rate sensitivity on localization and void coalescence. International Journal of Plasticity, volume 125, pages 265-279. https://doi.org/10.1016/j.ijplas.2019.09.007

Noticia en chino (chinese version) - distancing COVID-19

The effectiveness of social distancing strategies in the face of an epidemic has been analysed

Wed, 25 Mar 2020 12:53:18 +0100

The results, based on mathematical models and real-world data from the mobility flow of peoples, indicate that complete isolation of the population requires subsequently adopting active measures,otherwise, a new outbreak could occur. “Using contact matrices at this level of detail we can understand the effect of strategies such as closing schools, places of work or restaurants and other non-essential spaces”, explains Esteban Moro, a professor in the Department of Mathematics at the UC3M and co-author of this study, currently a guest professor at the MIT Media Lab.

“Before the need to adopt measures to contain and eradicate the current COVID-19 pandemic, we have simulated the evolution of the epidemic in a real-world population, in this case within the area of Boston. Our models show us that a new wave of infection is highly likely in almost all scenarios. The fundamental conclusion is that passive containment policies should be combined with other more aggressive measures,” noted Yamir Moreno, theoretical physicist, co-author of the study and responsible for the Group of Networks and Complex Systems (COSNET) at the Institute of Biocomputation and Physics of Complex Systems (BIFI) at the University of Zaragoza.

To conduct this research, the team of scientists used real-world mobility data from mobile phone users within the US,provided by Cuebiq Inc’s Data for good programme. Cuebiq Inc. is a company that records the locations of its users and aggregates them anonymously. They also analysed data from a Boston area census to construct a joint network of locations in three layers (community, schools and homes) and used the SIR model to model the spread of epidemics. “We are also currently working with real-world mobility data in New York City, which is the current epicentre for the epidemic in the US”, Esteban Moro noted. “If high resolution mobility data is available, our approach can be easily replicated for new cities or countries to measure the impact of social distancing strategies before the epidemic”, he added.

This research seeks to obtain data that will help to evaluate the impact of social distancing strategies that have been adopted in different countries in an effort to fight COVID-19, as well as define how long they should be in force and which are the most effective measures. They also analyse the probability that a second outbreak could occur later or the best way to prepare for a hypothetical second wave.

These preliminary results have just been published under a Creative Commons license on a website so that they are available to the authorities and scientific community, that can be used to contrast, update and optimise the analysis with new data. The company Zensei Technologies S.L., based in Madrid, is also collaborating on this project in response to the health crisis caused by COVID-19.

More information: Effectiveness of social distancing strategies for protecting a community from a pandemic with a data driven contact network based on census and real-world mobility data. David Martín-Calvo, Alberto Aleta, Alex Pentland, Yamir Moreno, Esteban Moro. https://covid-19-sds.github.io

A new type of acoustic insulation enables sound to be concentrated in corners

Tue, 29 Oct 2019 09:40:42 +0100

The research falls within the field of study of the condensed matter physics, more specifically the field of topological materials, which are solid and which behave as electrical insulators in their interior while allowing for electric conduction on the surface. Another feature that makes these materials interesting is that they are "topologically protected", that is, a signal remains robust and insensitive to the presence of impurities and defects of the material. Several recent research projects have shown that the higher order topological insulators can concentrate energy in corners. What the UC3M and NJU scientists have done is to “translate” this phenomenon, which is well-known in the theory of quantum physics, to classical acoustics in order to be able to focus acoustic energy in corners. The results were recently published in the journal Physical Review Letters.

To explain the process intuitively, the researchers use the sculpture “Organo” (Organ) by Eusebio Sempere as an example. Located in the gardens of the Fundación Juan March in Madrid (see image), this sculpture is composed of hollow aluminium bars which are separated from each other by a few centimetres and placed in a square lattice. In 1995, Spanish scientists showed that the sculpture was capable of attenuating sound.

Using this idea as a starting point, several studies have been carried out in which, by combining two crystals with different topologies, sound could be transported only through the interface between the two. “In this case, we have taken a further step. The study structure is formed by two sonic crystals with different topology concentrically placed. This new configuration means that the sound cannot be transmitted through the entire structure, but rather it is focused in the corners between the two crystals. The intensity of the sound in each of these corners will depend on the physical properties taken into account”, explains one of the authors of the study, Johan Christensen, from the Physics Department of UC3M.

These theoretical predictions have also been validated experimentally in an article published in the latest issue of the journal Advanced Materials. "Beyond its academic importance, we anticipate that the results obtained could be used to focus acoustic energy", adds another of the authors, María Rosendo López, a researcher from the PHONOMETA project at UC3M. Potential applications include the development of new waveguides, that is, physical structures which are used to guide sound waves. “We can achieve this without the need for a physical channel, but rather simply through the topology of the study system. This case of sound transport is relevant for filtering and conducting applications. Unlike traditional passive systems, this one is highly robust against imperfections”, says María Rosendo López.

Another potential application is acoustic-electric conversion. "Since we are able to concentrate the sound in the corners, harvest the acoustic energy, concentrate in the corners and then convert it into electrical energy”, the researchers add. These advances could also have applications in industrial ultrasound technologies or in the improvement of certain medical diagnostic tests such as ultrasound, for example.

This line of research is carried out within the framework of a broader scientific project, an ERC Starting Grant Horizon 2020 funded by the European Union (GA 714577) called “Frontiers in Phononics: Parity-Time Symmetric Phononic Metamaterials” (PHONOMETA). Within this context, its objective is to analyse and design a new generation of piezoelectric semiconductors that optimise the performance of complex acoustic systems.

Bibliographic references:

Zhang, Z. Rosendo López, M. Cheng, Y. Liu, X. Christensen, J. (2019): Non-Hermitian Sonic Second-Order Topological Insulator. Phys. Rev. Lett. 122, 195501. doi:10.1103/PhysRevLett.122.19550 e-Archivo de la UC3M: http://hdl.handle.net/10016/28492

Zhang, Z. Long, H. Liu, C. Shao, C. Cheng, Y. Liu, X. Christensen, J. (2019): Deep-Subwavelength Holey Acoustic Second-Order Topological Insulators. Adv. Mater. 2019. https://onlinelibrary.wiley.com/doi/full/10.1002/adma.201904682

Versión en chino (chinese version)

A study analyzes pre-installed software on Android devices and its privacy risks for users

Tue, 19 Mar 2019 12:03:19 +0100

The study shows, on the one hand, that the permission model on the Android operating system and its apps allow a large number of actors to track and obtain personal user information. At the same time, it reveals that the end user is not aware of these actors in the Android terminals or of the implications that this practice could have on their privacy. Furthermore, the presence of this privileged software in the system makes it difficult to eliminate it if one is not an expert user.

These results are detailed out in an article that will be made public on April 1 and which will be presented at one of the main cybersecurity and privacy conferences worldwide, the 41st IEEE Symposium on Security and Privacy, California (USA) under the title An Analysis of Pre-installed Android Software. The Agencia Española de Protección de Datos- AEPD (Spanish Data Protection Agency), which has contributed to the dissemination of this study because of the massive impact of the results on citizen privacy, will present the results before the European Commission for Data Protection.

Other findings

In addition to the standard permissions defined in Android and that can be controlled by the user, the researchers have identified more than 4,845 owner or personalized permissions by different actors in the manufacture and distribution of the terminals. This type of permission allows the apps advertised on Google Play to evade Android’s permission model to access user data without requiring their consent upon installation of a new app.

As for pre-installed apps on devices, 1,200 developers have been identified behind the pre-installed software, as well as the presence of more than 11,000 third party libraries (SDKs) included in the same. An important part of the libraries is related to advertising services and online tracking for commercial purposes. These pre-installed apps are executed with privileged permission and without being able, in the majority of cases, to be uninstalled from the system. An exhaustive analysis of the behavior of 50% of the identified apps reveal that many of them display potentially dangerous or undesired behavior.

In relation to the information offered upon logging into a new terminal, the lack of the apps transparency and of the Android operating system itself is brought to light, upon showing the user a list of permissions different from the real ones, thereby limiting capacity for decision-making regarding personal data management.

AEPD course of action

In accordance with a press release from the AEPD, this national agency will present this study and its conclusions to the working subgroups of the European Commission for Data Protection (ECDP), a European Union entity that forms a part of the Agency, together with other European data protection authorities and the European Supervisor. Among the functions of the ECDP is the fostering of cooperation among data protection agencies.

The Agency includes in the second central axis of its Strategic Plan (Innovation and Data Protection) the establishment of channels of collaboration with research groups, industry, and developers, with the objective of fomenting confidence in the digital economy in line with what is set out in the General Data Protection Regulation (GDPR). According to the Spanish Data Protection Agency, this study contributes to enabling manufacturers, developers and distributors to apply the principles of Privacy by Default and Design established in the GDPR and aimed at safeguarding the rights and freedom of individuals. Dissemination of the study undertaken by IMDEA Networks and UC3M forms part of these actions, independent of possible actions that may result from the powers and the coherent framework established by the GDPR.

Further information: Preliminary version of the study available here:
An Analysis of Pre-installed Android Software
Julien Gamba, Mohammed Rashed, Abbas Razaghpanah, Juan Tapiador, and Narseo Vallina-Rodriguez
https://haystack.mobi/papers/preinstalledAndroidSW_preprint.pdf
To appear in the 41st IEEE Symposium on Security and Privacy, (IEEE S&P 2020)

A study by the UC3M researches the limits of topological insulators using sound waves

Tue, 05 Mar 2019 09:57:03 +0100

In these kinds structures, sound signals remain robust and insensitive to noise caused by impurities and defects in the material. In the framework of this research, the scientists have discovered that the acoustic topological insulator could act as an extremely robust waveguide, capable of radiating sound in a very narrow ray towards the far field. This focused acoustic ray could be extremely important for applications such as non-destructive testing by ultrasound or in diagnostic ultrasound scans in medicine and biology, as pointed out by the researchers.

In the article, recently published in the journal Communications Physics along with physicists from the University of Nanjing (China) and the Stanford University (US), the scientists have reviewed the most recent studies on the development of this topic related to quantum physics. This area of research is at the forefront of physics and won the Nobel Prize in Physics 2016. The scientists who carried out this study wanted to see if the phenomenon of topological insulators, traditionally used in quantum physics to control electrical signals, could have an equivalent effect using sound waves.

“The idea was to use a concept so exotic it could produce completely new possibilities for acoustic transducers, sensors and waveguides. Moreover, from a more physical perspective, it would mean that certain effects in quantum physics have an equivalent in classic sound wave physics”, comments one of the authors of the study, Johan Christensen, from the Physics Department at the UC3M.

For this, the researchers wanted to emulate the so-called “valley-Hall effect”, used to investigate electrical conduction in different conductive and semi-conductive materials. This effect means that the magnetic field tends to separate the positive charges from the negative charges in opposite directions, so the “valleys” are maximums and minimums of electron energy in a crystal solid. The balance is restored when the force applied by the electric field generated by the distribution of charges opposes the force applied by the magnetic field. With the aim of emulating an acoustic version of this valley-Hall effect, the researchers created an artificial macroscopic crystal inspired by the weaving of Japanese baskets known as “kagome”, substituting the bamboo for small cylinders of epoxy resin. The functioning of this crystal was explained last year in several articles published by Johan Christensen in the scientific journals Advanced materials and Physical review letters.

“Curiously, the acoustic topological states related to the valley-Hall effect show a circulating vortex which, to our surprise, has produced unexpected and unprecedented properties for acoustics”, explains Johan Christensen. “Our Kagome crystal showed incredible resistance against pronounced defects, curves and turns when guiding the sound over the surface or interface of the crystal”.

This line of research is being developed as part of a wider scientific project, an ERC Starting Grant Horizon 2020 funded by the European Union (GA 714577) named “Frontiers in Phononics: Parity-Time Symmetric Phononic Metamaterials” (PHONOMETA). In this context, its aim is to analyse and design a new generation of piezoelectric semiconductors which allow the functioning of complex acoustic systems to be optimised.

Bibliography:

Zhang, X., Xiao, M., Cheng, Y., Lu, M-H, Christensen, J. (2018). Topological sound. Communications Physics, 1:97. 21 December 2018. http://hdl.handle.net/10016/28147

Wang, Mudi, Ye, Liping, Christensen, J., Liu, Zhengyou. (2018) Valley Physics in Non-Hermitian Artificial Acoustic Boron Nitride. Physical review letters, 120, 246601. 12 June 2018.
http://hdl.handle.net/10016/27424

Zhang, Zhiwang; Tian, Ye; Wang, Yihe; Gao, Shuxiang; Cheng, Ying; Liu, Xiaojun; Christensen, Johan. (2018) Directional Acoustic Antennas Based on Valley‐Hall Topological Insulators. Advanced Materials. Advanced materials, vol. 30, issue 36 (1803229). 30 July 2018.
http://hdl.handle.net/10016/27425

Version en chino (Chinese Version)

What atoms do when liquids and gases meet

Tue, 22 Jan 2019 10:21:54 +0100

When materials are in a solid state, their atoms are arranged in very uniform patterns, like grids, sheets and lattices. This means that, knowing the position of one atom, we can deduce the positions of all its neighbouring atoms. However, in liquids and gases, the arrangement of the atoms is very different, since they are subject to a disorderly motion. As a result of this motion, the atoms may be “locally” packed closely together for a moment, which leads to greater instantaneous density, and then separate. This only happens at microscopic scales; on larger scales, we are unable to discern this behaviour.

In order to explain these systems, the theory of capillary waves had been used successfully, which fits with the "drum skin" analogy. However, at smaller scales, this theory fails. For decades, all attempts to "adapt" it by means of small modifications have been unsuccessful and we have been unable to reproduce the experimental results and computer simulations. However, the authors of this study have found that a more microscopic (and, therefore, more fundamental) description can neatly explain these elusive results.

According to the authors of the study, the key lies in the fact that the functions that describe the arrangement of the atoms exhibit certain mathematical properties called "resonances" which, until now, had gone unnoticed. Taking these resonances into account, the mathematical consistency of the problem itself means the solution has to adopt a very particular form. "It's a completely new way of viewing the liquid-gas interface that can be applied to other systems; for example, by putting into contact two different liquids that do not mix,” explains one of the authors of the study, Professor Andrew Parry, from the Mathematics Department at Imperial College London.

"The most surprising thing for us was the simplicity and neatness of the mathematics of this theory and the fact that the theoretical models that we had all used for decades turn out to be, quite unexpectedly, special cases without any significance. Who would have suspected it?” says Carlos Rascón, co-author of the study and lecturer from the Mathematics Department at UC3M.

The study has not only given rise to a consistent description of the liquid-gas fluctuations but it has also, in an indirect fashion, allowed for the discovery of a family of theoretical models that can be solved analytically, without the need to use computer numerical calculations. Models with analytical solutions are always welcome in physics because they allow for a very useful comparison with more complex models. "In truth, these new analytical models are going to involve more work for us. Perhaps it would have been better not to have discovered them," jokes Carlos Rascón.

Bibliographic reference: A.O. Parry y C. Rascón. The Goldstone Mode and Resonances in the Fluid Interfacial Region. Nature Physics. 10 December 2018 https://www.nature.com/articles/s41567-018-0361-z

Videos from the Gallery of Fluid Motion

The UC3M wins the American Physical Society annual scientific video competition

Mon, 03 Dec 2018 10:23:55 +0100

The video “The shaky life of a water drop in an anise oil-rich environment”, made by the researchers from the UC3M Fluid Mechanics research group, Óscar Enríquez, Pablo Peñas-López and Javier Rodríguez-Rodríguez, was one of the winners of this international competition. The background music, a musical improvisation composed by Oscar Enríquez, is a musical trio made up of a clarinet, percussion and a violin that represent each of the three fluids.

“We had never seen anything like this, and we were quite surprised about what was happening”, comments Óscar Enríquez, lecturer from the UC3M Thermal and Fluids Engineering department and four times winner of the Gallery of Fluid Motion. “After several additional experiments, we observed that alcohol, somehow, allowed the anise oil to get inside the drop of water and form an emulsion (a collection of small drops of oil) within the drop. At the same time, the alcohol went in and mixed with the water, which caused the drop to grow, get less dense and be able to float”.

The other audio-visual piece from the UC3M that won the competition is called “Premixed flame oscillations in narrow channels”, and it was made by researchers Fernando Veiga López, Daniel Martínez Ruiz and Mario Sánchez Sanz, also from the Fluid Mechanics research group, and shows the effects of the fuel-air relationship in the form of a propane flame.

When the fuel-air relationship of a flame in a reduced space is increased beyond a critical value, thanks to the acoustic waves that are activated within the recipient, the front of the flame experiences dramatic waves. The team says that the work is relevant for engines and combustion chambers in gas turbines, which often experience the so-called thermoacoustic oscillations that can affect their operation.

The ‘Gallery of Fluid Motion’ competition is held as part of the American Physical Society’s annual meeting, the most important in the world for fluid mechanics. This competition, which intends to use the images’ ability to mix science and art in such a way as to attract the general public’s attention on research topics, is largely inspired by “An Album of Fluid Motion”, a book with black and white photos published in 1982 by Stanford engineering professor, Milton Van Dyke, who died in 2010.

For more information:

A research analyzes the connection between purchasing power and actions against climate change

Mon, 05 Nov 2018 12:23:54 +0100

To do so the researchers designed a “lab-in-the-field” experiment involving more than 320 individuals divided into 54 groups of 6 people. The experiment was conducted as follows. A total of 240 euros was given to each group of individuals. Each member of the group was given a specific amount of money. In half of the groups the 240 euros were divided evenly into 40 euros for each member. In the other half, the money was distributed unevenly in quantities from 20 to 60 euros. The experiment took place on the street and during the DAU table games fair organized by the Institute of Culture of Barcelona.

From here on, each person then had to contribute to a common fund in order to reach a specific goal, namely 120 euros to be used in an activity against climate change, in this case planting trees in Collserola. The participants were allowed to keep any money that was left over. At the start of the experiment, each participant knew how much money the other had and at the end of each round they could see how much money each person had contributed.

In this way, the researchers were able to test the economic effort that each individual was prepared to make for a common benefit, in this instance the fight against climate change. The results showed that, although all the groups achieved the collective goal of 120 euros, “the effort distribution was highly inequitable”, explained Jordi Duch, from the Alephsys (Algorithms Embedded in Physical Systems) research group at the Universitat Rovira i Virgili.

Specifically participants with fewer resources contributed significantly more to the public good than the richer, sometimes up to twice as much in relative terms. The researchers concluded that the poorest participants could be classified in two “generous behavior groups” whereas the richest were mostly classified into a “greedy cluster”.

The results suggest that future policies could be improved if they reinforced climate justice actions and taught the importance of fairness rather than focusing on teaching people about generic or global climate consequences, as the latter have not been proven to lead to equitable contributions.

“In fact, the study demonstrates once again that cooperation is better than competition at achieving socially desirable outcomes and that, in the case of climate change, cooperation is needed between all of the agents involved ”, said one of the other authors of the study, Anxo Sánchez, professor at the Department of Mathematics of the Universidad Carlos III de Madrid (UC3M).

Poorer and more vulnerable

The analysis of the results indicates that the groups in which the initial capital was evenly distributed showed two different types of behaviour: one where individuals contributed with quantities considered fair (approximately half of their initial capital), and another where people contributed with much more than was considered fair. Nevertheless, there were many differences in the groups in which the money was unevenly distributed from the start. Those with more money (50 or 60 euros) contributed less than was considered fair, in contrast to those who had less (20 or 30 euros), who proportionately contributed much more.

These results show that “given the inequalities, the poorest groups are the most vulnerable and, therefore, are the ones who suffer most” explained Julián Vicens, currently a researcher for the OpenSystems research group and member of the Institute of Complex Systems of the UB.

The experimental software, implemented on tablets, simulates strategic social interactions based on game theory and presents social dilemmas that generate tension between individual interest and the common good, whereas machine learning algorithms have been applied to identify patterns of behavior.

Bibliographic reference:

Julián Vicens, Nereida Bueno-Guerra, Mario Gutiérrez-Roig, Carlos Gracia-Lázaro, Jesús Gómez-Gardeñes, Josep Perelló, Angel Sánchez, Yamir Moreno, Jordi Duch. “Resource heterogeneity leads to unjust effort distribution in climate change mitigation”, Plos One, 30 octubre de 2018. https://doi.org/10.1371/journal.pone.0204369

The constructive role of noise

Thu, 04 Oct 2018 13:39:34 +0200

Until now, all methods for detecting very weak signals (with high frequencies) were based on the synchronization of that weak signal with a reference signal, that is why a signal of unknown frequency (such as, for example, an encrypted message or a barely audible fragment of information) could go unnoticed if it were "hidden" in a background of loud noise. Scientists have found a steady-state electronic system that produces consistent and stable oscillations of the current by applying a noise, which is called "coherent resonance". The frequency of these oscillations varies continuously in a wide range from zero to one hundred megahertz. If a weak frequency signal is also superimposed on that range, the system synchronizes with the weak signal, which is called stochastic resonance. This can be used to detect, process and interpret the weak signal, in a shorter period of time and without the need for a reference signal as with conventional methods.

These findings could be used to identify signals that are hidden in a large amount of noise or, reciprocally, to encrypt signals by wrapping them in background noise and recovering them later. For example, we could extract information from a conversation that had been recorded in a noisy room, astronomical observations masked by a large background noise could be analysed more efficiently, and it would even be possible to process image signals.

"Noise is usually a annoyance that we want to avoid and minimize in practical applications. However, there are times when noise plays a constructive role that can be used to produce useful results", says Luis L. Bonilla, researcher at the Department of Science and Materials Engineering and Chemical Engineering at the Instituto Gregorio Millán Barbany of the UC3M.

To demonstrate the existence of these resonances produced by noise and usable for the decoding of weak signals, the research team experimented with a superlattice of semiconductors that periodically alternates layers of gallium arsenide with others of a gallium arsenide alloy with 45 percent aluminium. The numerical simulations based on electron transport models were carried out at the Instituto Gregorio Millán and the Materials Department of the UC3M, and the laboratory experiments took place at the SINANO Institute in Suzhou and at the National University of Defence Technology (China) with samples created at the Paul Drude Institute in Berlin (Germany).

Bibliographical references:

Emanuel Mompo, Miguel Ruiz-Garcia, Manuel Carretero, Holger T. Grahn, Yaohui Zhang, Luis L. Bonilla, Coherence resonance and stochastic resonance in an excitable semiconductor superlattice. Physical Review Letters. https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.121.086805
Zhengzheng Shao, Zhizhen Yin, Helun Song, Wei Liu, Xiujian Li, Jubo Zhu, Klaus Biermann, Luis L. Bonilla, Holger T. Grahn, Yaohui Zhang, Fast Detection of a Weak Signal by a Stochastic Resonance Induced by a Coherence Resonance in an Excitable GaAs / Al 0.45 Ga 0.55 As Superlattice. Physical Review Letters. https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.121.086806

A scientific study characterises our circles of friendships

Tue, 24 Jul 2018 09:11:38 +0200

On average, there are three to five people in our lives with whom we have a very close relationship (close friends and/or family), around ten with whom we have close friendships, a larger group of about 30-35 people with whom we frequently interact and around one hundred acquaintances we come into contact with every now and then in our daily lives. In other words, we interact on a regular basis with about 150 people. This number is known as the "Dunbar number" and it indicates the amount of friends that our brain can handle, according to the theory formulated in the 1990’s by Robin Dunbar, Professor of Evolutionary Psychology at Oxford University, who also participates in this new scientific study.

"What our theory predicts and what we have now been able to ascertain is that people with a high cognitive capacity could potentially expand their circle of intimate friendships", explains Anxo Sánchez, a professor in UC3M’s Department of Mathematics and one of the authors of the study published in PNAS. This also happens in small communities, where there are fewer people available with whom to establish a relationship, leading to the broadening of the circle of close friendships among the people available: "It is the first time, as far as we know, that a purely mathematical theory, based on a basic physical principle (that of maximum entropy), predicts a social phenomenon or structure which is subsequently found in the data", says Anxo Sánchez.

Something similar happens in reverse, according to the researchers. "It is impossible to have relationships with 150 people and for them all to be intimate. Therefore, if one has a large number of relationships, it must mean that they are almost all superficial”, says another of the authors of the study, Ignacio Tamarit, from UC3M’s Interdisciplinary Group of Complex Systems, who is preparing his doctoral thesis on this subject.

When they began the study, carried out with the support of the BBVA Foundation’s Programme of Grants to Scientific Research Teams in the area of Digital Society and Economics, the researchers started with the hypothesis that human relationships involve a different degree of effort depending on their emotional intensity and that our ability to manage them is limited. Using standard techniques from statistical physics, they calculated the organisation in circles of friendship and uncovered the possibility of inverted regimes (that in small communities where there are fewer relationships, their intensity is greater). In order to verify this, data from communities of immigrants which were quite isolated - provided by an anthropologist from the Autonomous University of Barcelona, José Luis Molina - were used. After applying the theoretical model, they found the evidence they were looking for: "Our model explains the emergence of the structure in the organisation of personal networks”, says another of the researchers, José Cuesta, a professor in UC3M’s Department of Mathematics.

This study is part of IBSEN (Bridging the Gap: From Individual Behaviour to the Socio-tEchnical MaN), a European research project (FET Open Research and Innovation Action, H2020 Grant Agreement 662725) coordinated by UC3M which studies the behaviour of people at the individual level, especially when they are connected through new technologies such as mobile phones or social networks.

Bibliographic reference:

Cognitive resource allocation determines the organisation of personal networks. Ignacio Tamarit, José A. Cuesta, Robin I. M. Dunbar y Ángel Sánchez. Proceedings of the National Academy of Sciences (PNAS), July 23, 2018. DOI: www.pnas.org/cgi/doi/10.1073/pnas.1719233115

La NASA selecciona por sexta vez una imagen procesada por un profesor de la UC3M

Mon, 28 May 2018 08:52:02 +0200

El APOD es un sitio web de la NASA y la Universidad Tecnológica de Míchigan (EEUU) que selecciona cada día una imagen diferente del universo, junto con una breve explicación escrita por un astrónomo profesional. Arrancó el 16 de junio de 1995 y actualmente se ha convertido en una de las referencias de Internet para la comunidad astronómica mundial.

“Nunca pensé que en trece meses -tiempo que lleva mandando imágenes a la NASA- iba a conseguir colocar seis como foto del día y me parece increíble haberlo conseguido dos veces en esta semana”, comenta Domingo Pestana, que es profesor del departamento de Matemáticas de la UC3M y gran aficionado a la astrofotografía. Su APOD del pasado viernes corresponde a una imagen en la que aprecia un grupo de galaxias, denominado Abell S0740, que se encuentra a 450 millones de años luz de distancia de la Tierra.

Para conseguir esta imagen, Pestana ha procesado imágenes captadas por el Telescopio Espacial Hubble mediante un software español, Pixinsight, un programa de postproducción digital desarrollado por investigadores de la Universidad de Valencia que permite eliminar el ruido que contienen las imágenes en bruto captadas por las cámaras. “Descargo las imágenes originales de la NASA y comienzo a trabajar en ellas. En las originales prácticamente no se distingue nada, son muy oscuras, pero después de dedicar unas cuantas horas a su edición se consigue hacer aflorar detalles asombrosos”, explica Pestana.

“La galaxia elíptica gigante (en el centro derecha de la imagen) abarca más de 100.000 años luz y contiene alrededor de 100.000 millones de estrellas, con un tamaño comparable a nuestra propia galaxia espiral, la Vía Láctea“, explica la NASA en el APOD del día 25 de mayo. Los datos del Hubble pueden revelar una gran cantidad de detalles, incluso en galaxias tan distantes, como brazos y líneas de polvo espacial, cúmulos estelares, estructuras de anillos y arcos de lentes gravitacionales.

When the weather is good, we are happier on social networks

Thu, 26 Apr 2018 09:33:21 +0200

The study, published in the scientific journal PLOS ONE, was carried out by researchers from UC3M in collaboration with colleagues from the National Scientific Agency of Australia CSIRO (Commonwealth Scientific and Industrial Research Organisation), the Massachusetts Institute of Technology (MIT), the Institute of Electrical and Electronics Engineering (IEEE), the University of California in San Diego (USA), Monash University (Australia) and Stanford University (USA).

Based on the analysis of billions of Twitter and Facebook posts, the team of scientists has shown that we prefer warm, sunny days rather than days which are cold and wet. "Our study is the first to observe and measure the relationship between good weather and frame of mind using billions of posts on Twitter and Facebook in 75 metropolitan areas of the USA," says Esteban Moro,a professor in UC3M’s Mathematics Department and currently a visiting professor at the MIT Media Lab. While this has always been a fairly widespread popular belief, up to this point no such large-scale scientific study had been conducted that was able to draw statistically significant conclusions.

"We find that how we express ourselves is shaped by the weather outside. Adverse weather conditions —hot and cold temperatures, precipitation, added humidity, and increased cloud cover —reduce the sentiment of human expressions across billions of social media posts drawn from millions of US residents”, says another of the researchers, Nick Obradovich, of the MIT Media Lab.

To examine the association between weather conditions and expressed sentiments, the authors of the present study gathered 2.4 billion posts from Facebook and 1.1 billion from Twitter between the years 2009 and 2016. They analyzed the sentiment for each post using a special tool that categorizes posts based on keywords as positive or negative. To do this, they took account of the number of positive and negative words shared in the users’ posts and compared the results with the daily meteorological data for each location.

“The size of this effect is so significant that it could be placed in the same order of magnitude as the change of mood that occurs on social networks following events such as the earthquake in California in August 2014 or the San Bernardino shooting of December 2015, in which more than fourteen people were killed and twenty wounded”, says Esteban Moro.

The results obtained by the researchers could be used to anticipate what the effect of tomorrow’s weather will be on people’s frame of mind and thus to modify advertising campaigns, for example. It could also enable content providers to publish news in accordance with the emotional state of their audience or certain personal assistance systems, such as Alexa or Siri, to use this data in order to better tailor their messages to the needs of the user. Not to mention that if weather conditions worsen in the future, it may mean that our mood will also worsen.

Further information:

Patrick Baylis, Nick Obradovich, YuryKryvasheyeu, Haohui Chen, Lorenzo Coviello, Esteban Moro, Manuel Cebrian, James H. Fowler. Weather Impacts Expressed Sentiment. PLOS ONE, 2018. April 25, 2018.