The effect of heterogeneity on invasion in spatial epidemics: from theory to experimental evidence in a model system

Heterogeneity in host populations is an important factor affecting the ability of a pathogen to invade, yet the quantitative investigation of its effects on epidemic spread is still an open problem. In this paper, we test recent theoretical results, which extend the established “percolation paradigm” to the spread of a pathogen in discrete heterogeneous host populations. In particular, we test the hypothesis that the probability of epidemic invasion decreases when host heterogeneity is increased. We use replicated experimental microcosms, in which the ubiquitous pathogenic fungus Rhizoctonia solani grows through a population of discrete nutrient sites on a lattice, with nutrient sites representing hosts. The degree of host heterogeneity within different populations is adjusted by changing the proportion and the nutrient concentration of nutrient sites. The experimental data are analysed via Bayesian inference methods, estimating pathogen transmission parameters for each individual population. We find a significant, negative correlation between heterogeneity and the probability of pathogen invasion, thereby validating the theory. The value of the correlation is also in remarkably good agreement with the theoretical predictions. We briefly discuss how our results can be exploited in the design and implementation of disease control strategies

Complexity and anisotropy in host morphology make populations safer against epidemic outbreaks

One of the challenges in epidemiology is to account for the complex morphological structure of hosts such as plant roots, crop fields, farms, cells, animal habitats and social networks, when the transmission of infection occurs between contiguous hosts. Morphological complexity brings an inherent heterogeneity in populations and affects the dynamics of pathogen spread in such systems. We have analysed the influence of realistically complex host morphology on the threshold for invasion and epidemic outbreak in an SIR (susceptible-infected-recovered) epidemiological model. We show that disorder expressed in the host morphology and anisotropy reduces the probability of epidemic outbreak and thus makes the system more resistant to epidemic outbreaks. We obtain general analytical estimates for minimally safe bounds for an invasion threshold and then illustrate their validity by considering an example of host data for branching hosts (salamander retinal ganglion cells). Several spatial arrangements of hosts with different degrees of heterogeneity have been considered in order to analyse separately the role of shape complexity and anisotropy in the host population. The estimates for invasion threshold are linked to morphological characteristics of the hosts that can be used for determining the threshold for invasion in practical applications.Comment: 21 pages, 8 figure

A membrane parallel rapidly-exploring random tree algorithm for robotic motion planning

© 2020-IOS Press and the authors. All rights reserved. In recent years, incremental sampling-based motion planning algorithms have been widely used to solve robot motion planning problems in high-dimensional configuration spaces. In particular, the Rapidly-exploring Random Tree (RRT) algorithm and its asymptotically-optimal counterpart called RRT∗ are popular algorithms used in real-life applications due to its desirable properties. Such algorithms are inherently iterative, but certain modules such as the collision-checking procedure can be parallelized providing significant speedup with respect to sequential implementations. In this paper, the RRT and RRT∗ algorithms have been adapted to a bioinspired computational framework called Membrane Computing whose models of computation, a.k.a. P systems, run in a non-deterministic and massively parallel way. A large number of robotic applications are currently using a variant of P systems called Enzymatic Numerical P systems (ENPS) for reactive controlling, but there is a lack of solutions for motion planning in the framework. The novel models in this work have been designed using the ENPS framework. In order to test and validate the ENPS models for RRT and RRT*, we present two ad-hoc implementations able to emulate the computation of the models using OpenMP and CUDA. Finally, we show the speedup of our solutions with respect to sequential baseline implementations. The results show a speedup up to 6x using OpenMP with 8 cores against the sequential implementation and up to 24x using CUDA against the best multi-threading configuration

URBANIZACIÓN METROPOLITANA EN SUELO DE CONSERVACIÓN DEL VALLE DE MÉXICO

El proceso de urbanización de la Zona Metropolitana del Valle de México presenta al menos dos características, áreas compactas y dispersas; con procesos demográficos diferenciales, ralentizada en áreas consolidadas con redensificación intraurbana; en contraste con un incremento poblacional periférico, de baja densidad, que integran otros municipios a esta nueva dinámica de metropolización. La periferia metropolitana adquiere trascendencia por sus peculiaridades. Éste rápido proceso de urbanización periférico disperso, se asienta principalmente en suelo rural y de reserva ecológica, que se deriva de inversiones privadas en grandes proyectos de infraestructura y desarrollos inmobiliarios, combinadas con asentamientos humanos irregulares en suelo de alto valor social y ambiental y un mercado de suelo informal. Ambos procesos se enfrentan a través de nuevas políticas territoriales, con poco impacto, que han derivado en conflictos sociales y ambientales con los pueblos originarios, confrontando visiones sobre las nociones de desarrollo y de valor de uso del suelo. La llegada de nuevos gobiernos, federal y municipal, propician la coyuntura electoral actual, y establece un escenario de múltiples agendas para una planificación territorial alternativa. Por ello, el propósito de este trabajo consiste en examinar el proceso de urbanización en la periferia en suelo de conservación de la Zona Metropolitana del Valle de México a partir de la relación entre el crecimiento demográfico, el suelo de reserva ecológica y la intensidad de su uso, así como las contradicciones sociales y ambientales, y las alternativas en desarrollo. La hipótesis que orienta el trabajo parte de la idea que la política de planeación metropolitana es insuficiente al carecer de instrumentos para preservar el suelo de reserva ecológica. Además de la ausencia de recursos de suelo apto para la urbanización de los sectores sociales excluidos por el mercado y que optan por la ocupación ilegal. Así como, una política contradictoria al impulsar reformas que atentan a la preservación de las supuestas áreas protegidas, pero que estimulan la inversión privada inmobiliaria y los asentamientos irregulares, que en conjunto fortalece el mercado del suelo informal y formal como parte de un mismo proceso

Epidemics in Networks of Spatially Correlated Three-dimensional Root Branching Structures

Using digitized images of the three-dimensional, branching structures for root systems of bean seedlings, together with analytical and numerical methods that map a common 'SIR' epidemiological model onto the bond percolation problem, we show how the spatially-correlated branching structures of plant roots affect transmission efficiencies, and hence the invasion criterion, for a soil-borne pathogen as it spreads through ensembles of morphologically complex hosts. We conclude that the inherent heterogeneities in transmissibilities arising from correlations in the degrees of overlap between neighbouring plants, render a population of root systems less susceptible to epidemic invasion than a corresponding homogeneous system. Several components of morphological complexity are analysed that contribute to disorder and heterogeneities in transmissibility of infection. Anisotropy in root shape is shown to increase resilience to epidemic invasion, while increasing the degree of branching enhances the spread of epidemics in the population of roots. Some extension of the methods for other epidemiological systems are discussed.Comment: 21 pages, 8 figure

Oral mucosa: an alternative epidermic cell source to develop autologous dermal-epidermal substitutes from diabetic subjects

Oral mucosa has been highlighted as a suitable source of epidermal cells due to its intrinsic characteristics such as its higher proliferation rate and its obtainability. Diabetic ulcers have a worldwide prevalence that is variable (1%-11%), meanwhile treatment of this has been proven ineffective. Tissue-engineered skin plays an important role in wound care focusing on strategies such autologous dermal-epidermal substitutes. Objective The aim of this study was to obtain autologous dermal-epidermal skin substitutes from oral mucosa from diabetic subjects as a first step towards a possible clinical application for cases of diabetic foot. Material and Methods Oral mucosa was obtained from diabetic and healthy subjects (n=20 per group). Epidermal cells were isolated and cultured using autologous fibrin to develop dermal-epidermal in vitro substitutes by the air-liquid technique with autologous human serum as a supplement media. Substitutes were immunocharacterized with collagen IV and cytokeratin 5-14 as specific markers. A Student´s t- test was performed to assess the differences between both groups. Results It was possible to isolate epidermal cells from the oral mucosa of diabetic and healthy subjects and develop autologous dermal-epidermal skin substitutes using autologous serum as a supplement. Differences in the expression of specific markers were observed and the cytokeratin 5-14 expression was lower in the diabetic substitutes, and the collagen IV expression was higher in the diabetic substitutes when compared with the healthy group, showing a significant difference. Conclusion Cells from oral mucosa could be an alternative and less invasive source for skin substitutes and wound healing. A difference in collagen production of diabetic cells suggests diabetic substitutes could improve diabetic wound healing. More research is needed to determine the crosstalk between components of these skin substitutes and damaged tissues

Escala mexicana de calidad de vida laboral en personal sanitario: desarrollo y validación

There is little evidence of measurement scales with appropriate psychometric properties regard Quality of Work-Life in health personnel, so the objective was to develop and examine psychometric properties of Mexican Quality of Work Life Scale (MQWLS). An instrumental, cross-sectional study was conducted. Phase 1) development of the scale and content validity; Phase 2) validation with two different samples [n= 293] and [n = 300] through an online questionnaire. Content validity was obtained for 60 items (Aiken's V>.90); exploratory and confirmatory factor analyzes yielded a six-dimension structure; the fit indexes from the final scale with 24 items were acceptable (χ2[257]=540.277; CMIN/DF=2.102; NFI=.914; CFI=.953; GFI=.877, AGFI=.845; SRMR=.047; RMSEA=.061 [.054-.069] p .90); los análisis factoriales exploratorio y confirmatorio arrojaron una estructura de seis dimensiones; los índices de ajuste de la escala final con 24 ítems fueron aceptables (χ2[257]=540.277; CMIN/DF=2.102; NFI=.914; CFI=.953; GFI=.877, AGFI=.845; SRMR=.047; RMSEA=.061 [.054-.069] p<.001), con buenos índices de confiabilidad (α=.949, ω=.982). La EMCVL demostró confiabilidad en la consistencia interna, varias evidencias de validez y una invarianza configuracional y métrica aceptable con un modelo que confirma la existencia de seis dimensiones que explican el constructo a través de 24 ítems

Morphology and Size Differences between Local & High Redshift Luminous Infrared Galaxies

We show that the star-forming regions in high-redshift luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs) and submillimeter galaxies (SMGs) have similar physical scales to those in local normal star-forming galaxies. To first order, their higher infrared (IR) luminosities result from higher luminosity surface density. We also find a good correlation between the IR luminosity and IR luminosity surface density in starburst galaxies across over five orders of magnitude of IR luminosity from local normal galaxies to z ~ 2 SMGs. The intensely star-forming regions of local ULIRGs are significantly smaller than those in their high-redshift counterparts and hence diverge significantly from this correlation, indicating that the ULIRGs found locally are a different population from the high-redshift ULIRGs and SMGs. Based on this relationship, we suggest that luminosity surface density should serve as a more accurate indicator for the IR emitting environment, and hence the observable properties, of star-forming galaxies than their IR luminosity. We demonstrate this approach by showing that ULIRGs at z ~ 1 and a lensed galaxy at z ~ 2.5 exhibit aromatic features agreeing with local LIRGs that are an order of magnitude less luminous, but have similar IR luminosity surface density. A consequence of this relationship is that the aromatic emission strength in star-forming galaxies will appear to increase at z > 1 for a given IR luminosity compared to their local counterparts.Comment: Accepted for publication in The Astrophysical Journal; 13 pages, 7 figures; Online materials available at http://inthanon.as.arizona.edu/~wiphu/Rujopakarn_2010

Native bacteria isolated from roots and rhizosphere of Solanum lycopersicum L. increase tomato seedling growth under a reduced fertilization regime

In semiarid regions is important to use native strains best adapted to these environments to optimize plant-PGPR interaction. We aimed to isolate and characterize PGPR from roots and rhizosphere of a tomato crop, as well as studying the effect of its inoculation on tomato seedlings growth. We selected four strains considering their effectiveness of fixing nitrogen, solubilizing phosphate, producing siderophores and indole acetic acid. They belong to the genera Enterobacter, Pseudomonas, Cellulosimicrobium, and Ochrobactrum. In addition, we also analyzed the ability to solubilize Ca3(PO4)2, FePO4 and AlPO4 and the presence of one of the genes encoding the cofactor PQQ in their genome. Enterobacter 64S1 and Pseudomonas 42P4 showed the highest phosphorus solubilizing activity and presence of pqqE gene. Furthermore, in a tomato-based bioassay in speed-bed demonstrated that a sole inoculation at seedling stage with the strains increased dry weight of roots (49–88%) and shoots (39–55%), stem height (8–13%) and diameter (5–8%) and leaf area (22–31%) and were equal or even higher than fertilization treatment. Leaf nitrogen and chlorophyll levels were also increased (50–80% and 26–33%) compared to control. These results suggest that Enterobacter 64S1 and Pseudomonas 42P4 can be used as bio-inoculant in order to realize a nutrient integrated management.Fil: Pérez Rodriguez, María Micaela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Biología Agrícola de Mendoza. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Instituto de Biología Agrícola de Mendoza; ArgentinaFil: Piccoli, Patricia Noemí. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Biología Agrícola de Mendoza. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Instituto de Biología Agrícola de Mendoza; ArgentinaFil: Anzuay, María Soledad. Universidad Nacional de Río Cuarto; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Baraldi, Rita. Consiglio Nazionale delle Ricerche; ItaliaFil: Neri, Luisa. Consiglio Nazionale delle Ricerche; ItaliaFil: Taurian, Tania. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Río Cuarto; ArgentinaFil: Lobato Ureche, Miguel Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Biología Agrícola de Mendoza. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Instituto de Biología Agrícola de Mendoza; ArgentinaFil: Segura, Diana María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Biología Agrícola de Mendoza. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Instituto de Biología Agrícola de Mendoza; ArgentinaFil: Cohen, Ana Carmen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Biología Agrícola de Mendoza. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Instituto de Biología Agrícola de Mendoza; Argentin