Ernesto Estrada
Ernesto Estrada (born 2 May 1966) is a Cuban-Spanish scientist. He has been Senior ARAID Researcher at the Institute of Mathematics and Applications at the University of Zaragoza, Spain since 2019. Before that he was the chair in Complexity Science, and full professor at the Department of Mathematics and Statistics of the University of Strathclyde, Glasgow, United Kingdom. He is known by his contributions in different disciplines, including mathematical chemistry and complex network theory. Birth and education. Estrada was born in the city of Sancti Spiritus, in the central region of Cuba. Since the age of 11  he studied in a school which specialized in exact sciences. He later studied for a technical degree in Analytical chemistry in the technological institute IPQI Mártires de Girón Havana. At the age of 18 years, and before entering the university, he presented his first scientific paper in an international congress together with his mentor, Dr. Jose F. Fernández-Bertrán. The paper was about the detection of polyatomic anions in matrices of NaCl using Infrared spectroscopy. Between 1985 and 1990, he studied chemical sciences at the Central University of Las Villas in Santa Clara, Cuba, where he obtained his degree in  only 4 of the 5 years established for the program. In the first years after graduation, Estrada investigated on the organic synthesis and the use of spectroscopy for the characterization of new chemical entities with pharmacological activity. This research introduced him to the world of Computational chemistry due to the requirement of using efficient methods for drug design and drug discovery. He is one of the co-authors of the patent for the bactericide and fungicide drug Furvina. In 1997, he obtained his PhD in Mathematical chemistry under the direction of Prof. Luis A. Montero Cabrera on the topic of  Graph Theory Applied to Molecular Design. Academic career. After completing his PhD, Estrada spent some time as Research fellow at the University of Valencia, Spain with Prof. Jorge Galvez working on drug design and at the Hebrew University of Jerusalem with Prof. David Avnir working on molecular symmetry numbers and rotational partition functions. In 2000, he emigrated to Spain. Between 2002 and 2003, Estrada worked as a scientist at the Safety and Environmental Assurance Centre, Unilever in Colworth, U.K. He then obtained a position as "Ramón y Cajal" researcher at the University of Santiago de Compostela, Spain. Between 2008 and  2018, Estrada occupied the chair in Complexity Science at the University of Strathclyde. In 2019 he became ARAID Researcher at the University of Zaragoza. Research and achievements. Estrada has been a major contributor in the study of complex networks, where he has developed several approaches to investigate the network topology and network dynamics. An index introduced by him in 1999 to characterize the degree of protein folding, and then generalized to the study of complex networks in 2005, is nowadays widely known as the Estrada index of a graph or network. Estrada is also known in the field of spectral  graph theory where he has introduced several approaches to characterize the organizational architecture of Complex networks, such as the "subgraph centrality", "communicability", "spectral scaling", among others. His generalization of the discrete Laplace operator, as the d-path Laplacians and their transforms, has opened several new avenues for studying long-range interactions in network dynamics. Estrada is also known in the area of mathematical chemistry, in particular for the development and use of molecular descriptors based on the use of Graph Theory. In recent years he has developed mathematical approaches for the Hückel method or tight binding model, such as for  graph energy, "density matrix", "quantum molecular interference" in molecular electronics, among others. The last work is in collaboration with Nobel Prize in Chemistry Roald Hoffmann.