2,518 research outputs found
Complex network analysis and nonlinear dynamics
This chapter aims at reviewing complex network and nonlinear dynamical
models and methods that were either developed for or applied to socioeconomic
issues, and pertinent to the theme of New Economic Geography. After an introduction
to the foundations of the field of complex networks, the present summary
introduces some applications of complex networks to economics, finance, epidemic
spreading of innovations, and regional trade and developments. The chapter also
reviews results involving applications of complex networks to other relevant
socioeconomic issue
Complex networks analysis in socioeconomic models
This chapter aims at reviewing complex networks models and methods that were
either developed for or applied to socioeconomic issues, and pertinent to the
theme of New Economic Geography. After an introduction to the foundations of
the field of complex networks, the present summary adds insights on the
statistical mechanical approach, and on the most relevant computational aspects
for the treatment of these systems. As the most frequently used model for
interacting agent-based systems, a brief description of the statistical
mechanics of the classical Ising model on regular lattices, together with
recent extensions of the same model on small-world Watts-Strogatz and
scale-free Albert-Barabasi complex networks is included. Other sections of the
chapter are devoted to applications of complex networks to economics, finance,
spreading of innovations, and regional trade and developments. The chapter also
reviews results involving applications of complex networks to other relevant
socioeconomic issues, including results for opinion and citation networks.
Finally, some avenues for future research are introduced before summarizing the
main conclusions of the chapter.Comment: 39 pages, 185 references, (not final version of) a chapter prepared
for Complexity and Geographical Economics - Topics and Tools, P.
Commendatore, S.S. Kayam and I. Kubin Eds. (Springer, to be published
Production of ordered silicon nanocrystals by low-energy ion sputtering
We report on the production of ordered assemblies of silicon nanostructures
by means of irradiation of a Si(100) substrate with 1.2 keV Ar ions at normal
incidence. Atomic Force and High-Resolution Transmission Electron microscopies
show that the silicon structures are crystalline, display homogeneous height,
and spontaneously arrange into short-range hexagonal ordering. Under prolonged
irradiation (up to 16 hours) all dot characteristics remain largely unchanged
and a small corrugation develops at long wavelengths. We interpret the
formation of the dots as a result of an instability due to the sputtering yield
dependence on the local surface curvatureComment: 4 two-column pages (revtex4), 3 figures (higher quality copies in the
printed jrnl. version
Human Sexual Cycles are Driven by Culture and Match Collective Moods
It is a long-standing question whether human sexual and reproductive cycles
are affected predominantly by biology or culture. The literature is mixed with
respect to whether biological or cultural factors best explain the reproduction
cycle phenomenon, with biological explanations dominating the argument. The
biological hypothesis proposes that human reproductive cycles are an adaptation
to the seasonal cycles caused by hemisphere positioning, while the cultural
hypothesis proposes that conception dates vary mostly due to cultural factors,
such as vacation schedule or religious holidays. However, for many countries,
common records used to investigate these hypotheses are incomplete or
unavailable, biasing existing analysis towards primarily Christian countries in
the Northern Hemisphere. Here we show that interest in sex peaks sharply online
during major cultural and religious celebrations, regardless of hemisphere
location. This online interest, when shifted by nine months, corresponds to
documented human birth cycles, even after adjusting for numerous factors such
as language, season, and amount of free time due to holidays. We further show
that mood, measured independently on Twitter, contains distinct collective
emotions associated with those cultural celebrations, and these collective
moods correlate with sex search volume outside of these holidays as well. Our
results provide converging evidence that the cyclic sexual and reproductive
behavior of human populations is mostly driven by culture and that this
interest in sex is associated with specific emotions, characteristic of, but
not limited to, major cultural and religious celebrations.Comment: Main Paper: 21 pages, 4 figures Supplementary Material: 66 pages, 15
figures, 13 table
Molecular origin of high free energy barriers for alkali metal ion transfer through ionic liquidâgraphene electrode interfaces
In this work we study mechanisms of solvent-mediated ion interactions with charged surfaces in ionic liquids by molecular dynamics simulations, in an attempt to reveal the main trends that determine ionâelectrode interactions in ionic liquids. We compare the interfacial behaviour of Li+ and K+ at a charged graphene sheet in a room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate, and its mixtures with lithium and potassium tetrafluoroborate salts. Our results show that there are dense interfacial solvation structures in these electrolytes that lead to the formation of high free energy barriers for these alkali metal cations between the bulk and direct contact with the negatively charged surface. We show that the stronger solvation of Li+ in the ionic liquid leads to the formation of significantly higher interfacial free energy barriers for Li+ than for K+. The high free energy barriers observed in our simulations can explain the generally high interfacial resistance in electrochemical storage devices that use ionic liquid-based electrolytes. Overcoming these barriers is the rate-limiting step in the interfacial transport of alkali metal ions and, hence, appears to be a major drawback for a generalised application of ionic liquids in electrochemistry. Some plausible strategies for future theoretical and experimental work for tuning them are suggested
Reentrant phase behaviour for systems with competition between phase separation and self-assembly
In patchy particle systems where there is competition between the
self-assembly of finite clusters and liquid-vapour phase separation, reentrant
phase behaviour is observed, with the system passing from a monomeric vapour
phase to a region of liquid-vapour phase coexistence and then to a vapour phase
of clusters as the temperature is decreased at constant density. Here, we
present a classical statistical mechanical approach to the determination of the
complete phase diagram of such a system. We model the system as a van der Waals
fluid, but one where the monomers can assemble into monodisperse clusters that
have no attractive interactions with any of the other species. The resulting
phase diagrams show a clear region of reentrance. However, for the most
physically reasonable parameter values of the model, this behaviour is
restricted to a certain range of density, with phase separation still
persisting at high densities.Comment: 13 pages, 10 figure
Differences reported in the lifespan and aging of male Wistar rats maintained on diets containing fat with different fatty acid profiles (virgin olive, sunflower or fish oils) are not reflected by histopathological lesions found at death in central nervous and endocrine systems
The present study was designed to examine if dietary fat sources that have shown differences in lifespan and if
some aging-related aspects can modulate the range of histopathologic changes in central nervous and endocrine
systems that occur during the lifespan of Wistar rats. Moreover, it was attempted to gain insight into the relationship
between longevity and the development of the different pathological changes, as well as possible
interaction with diet. In order to achieve this, male Wistar rats were randomly assigned to three experimental
groups fed semisynthetic and isoenergetic diets from weaning until death with different dietary fat sources,
namely virgin olive, sunflower, or fish oil. An individual follow-up until death of each animal was performed.
Incidence, severity, and burden of specific or group (i.e., neoplastic or non-neoplastic proliferative and nonproliferative)
of lesions was calculated along with individualâs disease and individual organ lesion burden.
Most of the histopathological lesions found have been described in previous studies. Neoplasms, and in particular
pituitary adenomas followed by brain tumors, were the most prevalent lesions found in the rats and the main
cause of death involving both systems. Incidence of brain lesions was associated with age-at-death. Assayed
dietary fats did not present differential effects on pathological changes occurring in endocrine and central
nervous systems throughout rat lifespan.Spanish Government AGL2008-01057Government of Andalusia AGR83
Genetic divergence detected by ISSR markers and characterization of microsatellite regions in "Mytilus" mussels
[Abstract] The wide distribution of microsatellites in mussels of the Mytilus edulis complex (Mytilidae) enables the analysis of inter-simple-sequence repeat (ISSR) markers. The aim of this investigation was to assess genetic differentiation in six sampling localities distributed along the European Atlantic coast to expose the potential of these markers in genetic studies requiring the detection of low polymorphism and as a source of sequences for developing microsatellite markers. We detected low genetic structuring within each member of the Mytilus edulis complex. Nei and Li distances and AMOVA clustered the individuals studied into two groups. On the basis of these results two sampling localities coming from the M. edulis Ă M. galloprovincialis mosaic hybrid zone in Western Europe were assigned to one species. On the other hand, mussels of a sampling locality in the Baltic Sea were not significantly different from a pure M. edulis locality supporting an extensive introgression of M. edulis in these individuals. Finally, 148 microsatellites were found in the sequences of 51 ISSR markers, and two polymorphic microsatellite markers were developed.Xunta de Galicia; PGIDT10PX110304P
Preliminary Study of New Electrolytes Based on [MPPyr][TFSI] for Lithium Ion Batteries
Financiado para publicaciĂłn en acceso aberto: Universidade da Coruña/CISUG[Abstract] The application of ionic liquids in lithium ion batteries has increased in recent years in order to find new electrolytes that improve both performance and safety. The gathering of experimental data in order to understand the behaviour of these systems will help us design electrolytes that can be optimized for a specific objective. Data on electrolytes made up of a ternary mixture with an ionic liquid are missing in the literature. In this work, we provide new data on physical properties and refractive indexes for the ternary mixtures 1-methyl-1-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([MPPyr][TFSI]) + acetonitrile (AN) or Îł butyrolactone (GBL) or dimethyl sulfoxide (DMSO) + lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) with different concentrations of salt, specifically, 10%, 15%, 20%, 30%, 35%. The measured properties were density (Ï), viscosity (η) and ionic conductivity (Îș) in the temperature range of 278.15 to 358.15 K except for the mixtures with acetonitrile whose temperature range was 278.15 K to 328.15 K and the refractive indexes (nD) that were measured at a single temperature of 298.15 K. In general, the addition of salt in the binary mixtures provokes an increase of density and viscosity and therefore a decrease of ionic conductivity. It is worth mentioning that some of the studied systems showed values of ionic conductivity even better than those obtained for electrolyte systems based on carbonate.This work was supported by Ministerio de Economia y Competitividad (MINECO) and FEDER Program through the projects MAT2017â89239-C2â1-P, MAT2017â89239-C2â2-P and D2018â102679-T; Xunta de Galicia. Funding for open access charge: Universidade da Coruña/CISU
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