# Alberto Hernando de CastroKido Dynamics SA

Alberto Hernando de Castro

PhD

Cofounder & CEO @ Kido Dynamics SA

## About

68

Publications

7,681

Reads

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1,767

Citations

Introduction

Additional affiliations

January 2015 - June 2017

**Kido Dynamics SA**

Position

- co-founder & CTO

## Publications

Publications (68)

Cultural landscapes often pose problems for planning and management because of insufficient information regarding visitor movements, interests and infrastructure burden. Traditionally visitor surveys have helped to fill this gap, albeit limited to their incomplete and occasional nature. This paper presents a methodology for using cellular antenna m...

The urban spatial structure represents the distribution of public and private spaces in cities and how people move within them. Although it usually evolves slowly, it can change quickly during large-scale emergency events, as well as due to urban renewal in rapidly developing countries. Here we present an approach to delineate such urban dynamics i...

The urban spatial structure represents the distribution of public and private spaces in cities and how people move within them. While it usually evolves slowly, it can change fast during large-scale emergency events, as well as due to urban renewal in rapidly developing countries. This work presents an approach to delineate such urban dynamics in q...

Assessing the impact of mobility on epidemic spreading is of crucial importance for understanding the effect of policies like mass quarantines and selective re-openings. While many factors affect disease incidence at a local level, making it more or less homogeneous with respect to other areas, the importance of multi-seeding has often been overloo...

Following its emergence in late 2019, the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)1,2 has been tracked via phylogenetic analysis of viral genome sequences in unprecedented detail3–5. While the virus spread globally in early 2020 before borders closed, intercontinental travel has since been greatly reduced. However, wit...

Total and perimetral lockdowns were the strongest nonpharmaceutical interventions to fight against Covid-19, as well as the with the strongest socioeconomic collateral effects. Lacking a metric to predict the effect of lockdowns in the spreading of COVID-19, authorities and decision-makers opted for preventive measures that showed either too strong...

We show how Zipf's law arises from a variational principle related to the scaling invariance of the Cramer–Rao inequality. It is not an ad-hoc mathematical expression but emerges from variation of Fisher's information measure. We relate Fisher information to references in physics journals. The pertinent citations follow Zipf's law.

This paper deals primarily with relatively novel thermal quantifiers called disequilibrium and statistical complexity, whose role is growing in different disciplines of physics and other sciences. These quantifiers are called L. Ruiz, Mancini, and Calvet (LMC) quantifiers, following the initials of the three authors who advanced them. We wish to es...

In this paper we establish information theoretical bridges between 1) Thermal Heisenberg uncertainties $\Delta x \Delta p$ (at temperature $T$), and 2) LMC structural quantifiers. After having achieved such purpose, we determine to what an extent our bridges can be extended to both the semi classical and classical realms. Also, we find a strict bou...

Many countries established strong population lockdowns as a response to the pandemic of COVID-19 in 2020. While these measures proved efficient in stopping the spreading of the virus, they also introduced collateral effects in the economies of these countries. We report in this work that the imprints in mobility of both the lockdown and post-lockdo...

Assessing the impact of mobility on epidemic spreading is of crucial importance for understanding the effect of policies like mass quarantines and selective re-openings. High mobility between areas contribute to the importation of cases, affecting the spread of the disease. While many factors influence local incidence and making it more or less hom...

As part of the effort undertaken to understand urban environments and their generation, we need to explore models that produce statistically valid configurations of roads. These sort of models will help us to derive plausible mechanisms for the spatial location of population. This task is of fundamental importance, as we need to create an experimen...

The relaxation of photoexcited nanosystems is a fundamental process of light–matter interaction. Depending on the couplings of the internal degrees of freedom, relaxation can be ultrafast, converting electronic energy in a few fs, or slow, if the energy is trapped in a metastable state that decouples from its environment. Here, we study helium nano...

The relaxation of photoexcited nanosystems is a fundamental process of light-matter interaction. Depending on the couplings of the internal degrees of freedom, relaxation can be ultrafast, converting electronic energy in a few fs, or slow, if the energy is trapped in a metastable state that decouples from its environment. Here, helium nanodroplets...

During the last decade, density function theory (DFT) in its static and dynamic time dependent forms, has emerged as a powerful tool to describe the structure and dynamics of doped liquid helium and droplets. In this review, we summarise the activity carried out in this field within the DFT framework since the publication of the previous review art...

We analyze an exhaustive data-set of new-cars monthly sales. The set refers to 10 years of Spanish sales of more than 6500 different car model configurations and a total of 10M sold cars, from January 2007 to January 2017. We find that for those model configurations with a monthly market-share higher than 0.1\% the sales become scalable obeying Gib...

We present a joint experimental and theoretical study on the desolvation of Ba+ cations in 4He nanodroplets excited via the 6p 6s transition. The experiments reveal an efficient desolvation process yielding mainly bare Ba+ cations and Ba+Hen exciplexes with n = 1 and 2. The speed distributions of the ions are well described by a Maxwell-Boltzmann d...

The distribution of firms’ growth and firms’ sizes is a topic under intense
scrutiny. In this paper, we show that a thermodynamic model based on the
maximum entropy principle, with dynamical prior information, can be
constructed that adequately describes the dynamics and distribution of
firms’ growth. Our theoretical framework is tested against a c...

In view of promising applications of fractal nanostructures, we analyze the
spectra of quantum particles in the Sierpinski carpet and study the
non-correlated electron gas in this geometry. We show that the spectrum
exhibits scale invariance with almost arbitrary spacing between energy levels,
including large energy gaps at high energies. These fea...

The dynamics of Na atoms on the surface of helium nanodroplets following excitation via the 3p <-- 3s transition has been investigated using state-specific ion-based detection of the products. Excitation of the system to the 3p 2Pi states is found to lead to the desorption of both bare Na and NaHe exciplexes. The associated speed distributions poin...

A quantitative understanding of cities' demographic dynamics is becoming a
potentially useful tool for planning sustainable growth. The concomitant theory
should reveal details of the cities' past and also of its interaction with
nearby urban conglomerates for providing a reasonably complete picture. Using
the exhaustive database of the Census Bure...

The dynamics following the photoionization of neutral Rb and Cs atoms residing in a dimple at the surface of a superfluid $^{4}\mathrm{He}_{1000}$ nanodroplet has been investigated within time-dependent density functional theory, complementing a previous study on Ba. The calculations reveal that structured high density helium solvation layers form...

Within Density Functional Theory (DFT), we address the capture of a Cs atom by a helium nanodroplet using models of different complexity. In the simplest model, the Cs-droplet potential is obtained in two extreme approximations, namely the sudden approximation in which one assumes that the density of the droplet is not relaxed as Cs approaches it,...

We present a combined ion imaging and density functional theory study of the
dynamics of the desorption process of rubidium and cesium atoms off the surface
of helium nanodroplets upon excitation of the perturbed $6s$ and $7s$ states,
respectively. Both experimental and theoretical results are well represented by
the pseudodiatomic model for effect...

Whereas most of the phenomena associated with superfluidity have been observed in finite-size helium systems, the nucleation of quantized vortices has proven elusive. Here we show using time-dependent density functional simulations that the solvation of a Ba(+) ion created by photoionization of neutral Ba at the surface of a (4)He nanodroplet leads...

Understanding demographic and migrational patterns constitutes a great challenge. Millions of individual decisions, motivated by economic, political, demographic, rational and/or emotional reasons underlie the high complexity of demographic dynamics. Significant advances in quantitatively understanding such complexity have been registered in recent...

The theory of photofragments angular momentum polarization is applied to the photodetachment of an electronically excited alkali atom from a helium nanocluster (N = 200). The alignment of the electronic angular momentum of the bare excited alkali atoms produced is calculated quantum mechanically by solving the excited states coupled equations with...

The best-known property of superfluid helium is the vanishing viscosity that objects experience while
moving through the liquid with speeds below the so-called critical Landau velocity. This critical velocity
is generally considered a macroscopic property as it is related to the collective excitations of the helium
atoms in the liquid. In the prese...

The dynamics following the photoexcitation of Ag atoms in (4)He nanodroplets via the 5p (2)P1/2 ← 5s (2)S1/2 and 5p (2)P3/2 ← 5s (2)S1/2 transitions has been investigated in a joint experimental and theoretical effort. It has been experimentally found that upon excitation to the (2)P1/2 state, the Ag atoms are ejected with a speed distribution peak...

An imaginary-time nonuniform mesh method is presented and used to find the
first 50 eigenstates and energies of up to five strongly interacting spinless
quantum Lennard-Jones particles trapped in a one-dimensional harmonic
potential. We show that the use of tailored grids reduces drastically the
computational effort needed to diagonalize the Hamilt...

We present an exhaustive study of the rank-distribution of city-population and population-dynamics of the 50 Spanish provinces (more than 8000 municipalities) in a time-window of 15 years (1996–2010). We exhibit compelling evidence regarding how well the MaxEnt principle describes the equilibrium distributions. We show that the microscopic dynamics...

Orderliness, reflected via mathematical laws, is encountered in different
frameworks involving social groups. Here we show that a thermodynamics can be
constructed that macroscopically describes urban population flows. Microscopic
dynamic equations and simulations with random walkers underlie the macroscopic
approach. Our results might be regarded,...

The Ca(2) → Ca(4s4p (1)P) + Ca(4s(2) (1)S) photodissociation was investigated in a He droplet isolation experiment where the droplets are doped by Ar atoms. Fluorescence spectra associated with the Ca(4s4p (1)P → 4s(2) (1)S) emission were recorded as a function of the average number of Ar atoms per droplet. Three contributions were observed dependi...

The stability of the ground or excited state calcium atom in an argon-doped helium droplet has been investigated using an extension of the helium density functional method to treat clusters. This work was motivated by the experimental study presented in a companion paper, hereafter called Paper I [A. Masson, M. Briant, J. M. Mestdagh, M. A. Gaveau,...

Evidences are presented concerning tantalizing regularities in cities'
population-flows in what regards to space and time correlations. The former
exhibit a distance-behavior (for large distances) compatible with the inverse
square law, following an overall Lorentzian dependence with an scale-parameter
of $74\pm6$ km. The later decay exponentially...

MaxEnt's variational principle, in conjunction with Shannon's logarithmic
information measure, yields only exponential functional forms in
straightforward fashion. In this communication we show how to overcome this
limitation via the incorporation, into the variational process, of suitable
dynamical information. As a consequence, we are able to for...

On the basis of dynamical principles we derive the Logistic Equation (LE),
widely employed (among multiple applications) in the simulation of population
growth, and demonstrate that scale-invariance and a mean-value constraint are
sufficient and necessary conditions for obtaining it. We also generalize the LE
to multi-component systems and show tha...

The dynamics following the photoexcitation of Na and Li atoms located on the surface of helium nanodroplets has been investigated in a joint experimental and theoretical study. Photoelectron spectroscopy has revealed that excitation of the alkali atoms via the (n + 1)s ←ns transition leads to the desorption of these atoms. The mean kinetic energy o...

The MaxEnt solutions are shown to display a variety of behaviors (beyond the
traditional and customary exponential one) if adequate dynamical information is
inserted into the concomitant entropic-variational principle. In particular, we
show both theoretically and numerically that power laws and power laws with
exponential cut-offs emerge as equili...

We present a theoretical study of argon adsorption on a model aluminium substrate structured with cylindrical nanopores. We employ state-of-the-art computational methods to obtain (i) accurate three-dimensional adsorption potentials for the nanostructured substrate starting from the corresponding ab initio physisorption potential for a planar surfa...

We theoretically describe the absorption spectrum of atomic impurities in isotopic mixtures of liquid helium within a zero-temperature density functional approach. Two situations are considered. In the first one, the absorption spectrum of Na atoms attached to He41000-He3N3 droplets with N3 values from 100 to 3000 is presented as a case study of an...

We investigate the wetting behavior of helium on nanostructured alkali metal surfaces, at temperatures below and slightly above the bulk superfluidity threshold. Starting from a determination of the phase diagram of helium on semiinfinite planar C sup to 3 K, performed within finite-range, temperature-dependent density functional theory, we examine...

We have studied helium drops doped with Li atoms within finite-range density functional theory using Li–He pair potentials obtained by the multireference configuration interaction method combined with augmented core-valence correlation consistent basis sets of quintuple-zeta quality. The absorption spectrum of Li around the 2p ← 2s transition has b...

We investigate the wetting behavior of helium on nanostructured alkali metal surfaces, at temperatures below and slightly above the bulk superfluidity threshold. Starting from a determination of the phase diagram of helium on semiinfinite planar Cs up to 3 K, performed within finite–range, temperature–dependent density functional theory, we examine...

We present a thermodynamic formulation for scale-invariant systems based on the minimization with constraints of the Fisher information measure. In such a way a clear analogy between these systems’ thermal properties and those of gases and fluids is seen to emerge in a natural fashion. We focus our attention on the non-interacting scenario, speakin...

Within finite-range density-functional theory, we have addressed the infrared absorption and emission spectrum of electron
bubbles attached to linear vortices in liquid 4He as a function of pressure. We have found that the presence of vortices affects very little the absorption spectrum, only
causing a small shift in the 1s→2p peak. The energy of t...

Zipf's law is shown to arise as the variational solution of a problem
formulated in Fisher's terms. An appropriate minimization process involving
Fisher information and scale-invariance yields this universal rank
distribution. As an example we show that the number of citations found in the
most referenced physics journals follows this law.

Experimental and theoretical results for mixed helium droplets doped with one calcium atom are reported. The absorption spectrum around the 4s4p <- 4s(2) transition is calculated as a function of the composition of the droplet and compared to the experiment. Our study reveals the distinct feature that for specific He-3 concentrations, Ca atoms sit...

The minimization of Fisher’s information (MFI) approach of Frieden et al. [Phys. Rev. E 60, 48 (1999)] is applied to the study of size distributions in social groups on the basis of a recently established analogy between scale invariant systems and classical gases [Phys. A 389, 490 (2010)]. Going beyond the ideal gas scenario is seen to be tantamou...

We have determined the structure of 4He droplets doped with one or two magnesium atoms. Our results are used to interpret recent resonant two-photon-ionization (R2PI) and laser induced fluorescence (LIF) experiments. We argue that the Mg radial delocalization inside large 4He droplets may reconcile the apparently contradictory solvation properties...

We investigate the effects (on the wetting characteristics of helium below 3 K) of tailoring an alkali-metal surface by incorporating a regular array of nanoscopic indentations. We establish the prewetting line of helium on semi-infinite planar Cs up to 3 K in the frame of a finite-range temperature-dependent density-functional theory, and examine...

We present a thermodynamic formulation for scale-invariant systems based on the principle of extreme information. We create an analogy between these systems and the well-known thermodynamics of gases and fluids, and study as a compelling case the non-interacting system -the scale-free ideal gas- presenting some empirical evidences of electoral resu...

We present an analysis of the electronic 3p←3s excitation of Na atoms attached to 3He and 4He droplets. Once the ground state structure of the doped drops has been obtained within finite-range density functional theory,
we determine the time-correlation function of the Na atom evolving in the full three-dimensional 2Π1/2, 2Π3/2 and 2Σ1/2 potentials...

We report studies of adsorption of helium in translationally invariant polygonal pores at zero temperature, with emphasis on the route to capillary condensation and the appearance of metastable states. We analyze hysteresis and hysterectic-like phenomena associated to the existence of multiple equilibrium states in a rhombic pore and examine the ef...

We have studied the structure of $^{4}\text{H}\text{e}$ droplets doped with magnesium atoms using density functional theory. We have found that the solvation properties of this system strongly depend on the size of the $^{4}\text{H}\text{e}$ droplet. For small drops, Mg resides in a deep surface state, whereas for large-size drops it is fully solva...

We report studies of adsorption of helium in translationally invariant polygonal pores at zero temperature, with emphasis on the route to capillary condensation and the appearance of metastable states. We analyze hysteresis and hysterectic-like phenomena associated to the existence of multiple equilibrium states in a rhombic pore and examine the ef...

We have studied the structure of $^4$He droplets doped with magnesium atoms using density functional theory. We have found that the solvation properties of this system strongly depend on the size of the $^4$He droplet. For small drops, Mg resides in a deep surface state, whereas for large size drops it is fully solvated but radially delocalized in...

We have recently shown that the adsorption potential for a solid with a planar surface can be derived from a unique elementary source field which can be applied to other geometries. We review this procedure, discuss limitations of previous approximations and present new results for adsorption of helium in hexagonal pores.

We investigate adsorption of helium in nanoscopic polygonal pores at zero temperature using a finite-range density functional theory. The adsorption potential is computed by means of a technique denoted as the elementary source method. We analyze a rhombic pore with Cs walls, where we show the existence of multiple interfacial configurations at som...

Within density functional theory, we have obtained the structure of (4)He droplets doped with neutral calcium atoms. These results have been used, in conjunction with newly determined ab initio (1)Sigma and (1)Pi Ca-He pair potentials, to address the 4s4p (1)P(1)<- 4s(2) (1)S(0) transition of the attached Ca atom, finding a fairly good agreement wi...

The absorption spectra of the first electronic exited state of alkali metal atoms on helium nanodroplets formed of both 4He and 3He isotopes were studied experimentally as well as theoretically. In the experimental part new data on the 2p<--2s transition of lithium on 3He nanodroplets are presented. The absorption spectrum changes drastically when...

We present a method to compute, assuming a continuous distribution of sources, the elementary potential created by a differential element of volume of matter, whose integral generates a known adsorption field V(z) for a planar surface. We show that this elementary potential is univocally determined by the original field and can be used to generate...

Electron bubbles in superfluid (4)He have been recently observed in low-temperature cavitation measurements under experimental conditions where quantized vortices are also present in the liquid, and which might be attached to the bubbles. We have calculated, within density functional theory, the structure and energetics of electron bubbles pinned t...

We present systematic results, based on density functional calculations, for the structure and energetics of $^3$He and $^4$He nanodroplets doped with alkaline earth atoms. We predict that alkaline earth atoms from Mg to Ba go to the center of $^3$He drops, whereas Ca, Sr, and Ba reside in a deep dimple at the surface of $^4$He drops, and Mg is at...

We present a formulation of a Fisher-based thermodynamics for scale invariant systems. We study the special case of non-interacting components, what we call the scale-free ideal gas or Zipf- Mandelbrot gas. We find that the density distribution function for the equilibrium state obeys the empirical regularity known as Zipf's law, whereas non-equili...