Stability Analysis of a Hybrid Cellular Automaton Model of Cell Colony Growth

Cell colonies of bacteria, tumour cells and fungi, under nutrient limited growth conditions, exhibit complex branched growth patterns. In order to investigate this phenomenon we present a simple hybrid cellular automaton model of cell colony growth. In the model the growth of the colony is limited by a nutrient that is consumed by the cells and which inhibits cell division if it falls below a certain threshold. Using this model we have investigated how the nutrient consumption rate of the cells affects the growth dynamics of the colony. We found that for low consumption rates the colony takes on a Eden-like morphology, while for higher consumption rates the morphology of the colony is branched with a fractal geometry. These findings are in agreement with previous results, but the simplicity of the model presented here allows for a linear stability analysis of the system. By observing that the local growth of the colony is proportional to the flux of the nutrient we derive an approximate dispersion relation for the growth of the colony interface. This dispersion relation shows that the stability of the growth depends on how far the nutrient penetrates into the colony. For low nutrient consumption rates the penetration distance is large, which stabilises the growth, while for high consumption rates the penetration distance is small, which leads to unstable branched growth. When the penetration distance vanishes the dispersion relation is reduced to the one describing Laplacian growth without ultra-violet regularisation. The dispersion relation was verified by measuring how the average branch width depends on the consumption rate of the cells and shows good agreement between theory and simulations.Comment: 8 pages, 6 figure

A Liposomal Formulation to Exploit the Bioactive Potential of an Extract from Graciano Grape Pomace

Antioxidant compounds with health benefits can be found in food processing residues, such as grape pomace. In this study, antioxidants were identified and quantified in an extract obtained from Graciano red grape pomace via a green process. The antioxidant activity of the extract was assessed by the DPPH and FRAP tests, and the phenolic content by the Folin–Ciocalteu test. Furthermore, nanotechnologies were employed to produce a safe and effective formulation that would exploit the antioxidant potential of the extract for skin applications. Anthocyanins, flavan-3-ols and flavanols were the main constituents of the grape pomace extract. Phospholipid vesicles, namely liposomes, were prepared and characterized. Cryo-TEM images showed that the extract-loaded liposomes were predominantly spherical/elongated, small, unilamellar vesicles. Light scattering results revealed that the liposomes were small (~100 nm), homogeneously dispersed, and stable during storage. The non-toxicity of the liposomal formulation was demonstrated in vitro in skin cells, suggesting its possible safe use. These findings indicate that an extract with antioxidant properties can be obtained from food processing residues, and a liposomal formulation can be developed to exploit its bioactive value, resulting in a promising healthy product

Gut Microbiota Elicits a Protective Immune Response against Malaria Transmission

SummaryGlycosylation processes are under high natural selection pressure, presumably because these can modulate resistance to infection. Here, we asked whether inactivation of the UDP-galactose:β-galactoside-α1-3-galactosyltransferase (α1,3GT) gene, which ablated the expression of the Galα1-3Galβ1-4GlcNAc-R (α-gal) glycan and allowed for the production of anti-α-gal antibodies (Abs) in humans, confers protection against Plasmodium spp. infection, the causative agent of malaria and a major driving force in human evolution. We demonstrate that both Plasmodium spp. and the human gut pathobiont E. coli O86:B7 express α-gal and that anti-α-gal Abs are associated with protection against malaria transmission in humans as well as in α1,3GT-deficient mice, which produce protective anti-α-gal Abs when colonized by E. coli O86:B7. Anti-α-gal Abs target Plasmodium sporozoites for complement-mediated cytotoxicity in the skin, immediately after inoculation by Anopheles mosquitoes. Vaccination against α-gal confers sterile protection against malaria in mice, suggesting that a similar approach may reduce malaria transmission in humans.PaperFlic

Near-threshold high spin amplification in a 1300 nm GaInNAs spin laser

Using continuous-wave optical pumping of a spin-VCSEL at room temperature, we find high spin amplification of the pump close to threshold within the communications wavelength window, here at 1300 nm. This facilitates a strong switch from left to right circularly polarised light emission, which has potential applications in polarisation encoding for data communications. We use a simple spin flip model to fit the experimental results and discuss the VCSEL parameters that affect this amplification

Stepwise strategy based on 1H-NMR fingerprinting in combination with chemometrics to determine the content of vegetable oils in olive oil mixtures

1H NMR fingerprinting of edible oils and a set of multivariate classification and regression models organised in a decision tree is proposed as a stepwise strategy to assure the authenticity and traceability of olive oils and their declared blends with other vegetable oils (VOs). Oils of the ‘virgin olive oil’ and ‘olive oil’ categories and their mixtures with the most common VOs, i.e. sunflower, high oleic sunflower, hazelnut, avocado, soybean, corn, refined palm olein and desterolized high oleic sunflower oils, were studied. Partial least squares (PLS) discriminant analysis provided stable and robust binary classification models to identify the olive oil type and the VO in the blend. PLS regression afforded models with excellent precisions and acceptable accuracies to determine the percentage of VO in the mixture. The satisfactory performance of this approach, tested with blind samples, confirm its potential to support regulations and control bodies

Polarisation Patterns and Vectorial Defects in Type II Optical Parametric Oscillators

Previous studies of lasers and nonlinear resonators have revealed that the polarisation degree of freedom allows for the formation of polarisation patterns and novel localized structures, such as vectorial defects. Type II optical parametric oscillators are characterised by the fact that the down-converted beams are emitted in orthogonal polarisations. In this paper we show the results of the study of pattern and defect formation and dynamics in a Type II degenerate optical parametric oscillator for which the pump field is not resonated in the cavity. We find that traveling waves are the predominant solutions and that the defects are vectorial dislocations which appear at the boundaries of the regions where traveling waves of different phase or wave-vector orientation are formed. A dislocation is defined by two topological charges, one associated with the phase and another with the wave-vector orientation. We also show how to stabilize a single defect in a realistic experimental situation. The effects of phase mismatch of nonlinear interaction are finally considered.Comment: 38 pages, including 15 figures, LATeX. Related material, including movies, can be obtained from http://www.imedea.uib.es/Nonlinear/research_topics/OPO

Ethnic diversity in children's television: the case of Sofía the First

Miriam E. Aguasanta-Regalado – Universidad de Valencia - 0000-0003-2917-4111Juana M. Encarnación Cruz – Universidad Autónoma de Santo Domingo - 0000-0001-7542-3524Flor B. Fortuna Terrero – Universidad Autónoma de Santo Domingo - 0000-0002-7201-4749Ángel San Martín Alonso – Universidad de Valencia - 0000-0003-3565-4250Isabel M. Gallardo-Fernández – Universidad de Valencia - 0000-0001-7505-5469Recepción: 05.04.2022 | Aceptado: 18.04.2022Correspondencia a través de ORCID: Miriam E. Aguasanta-Regalado - 0000-0003-2917-4111Los medios de comunicación se han convertido en prescriptores sociales. Por ello es cada vez más importante examinar cómo estos dibujan y describen el contexto social, así como representan al otro. Problema de estudio: ¿cómo se construye la representación de la diversidad étnica en una serie infantil de televisión? Se hace uso del Análisis Crítico del Discurso como herramienta que permite examinar críticamente la imagen de la diversidad en el relato infantil. A la luz de la revisión se observa una mejora en la parte cuantitativa, presentando un mayor número de personajes de color. Se estima que la educación mediática es la estrategia idónea para desarrollar la capacidad de análisis crítico de los contenidos audiovisuales. Abstract: The media have become social prescribers. For this reason, it is increasingly important to examine how they draw and describe the social context, as well as how they represent the other. It is questioned how the representation of ethnic diversity is constructed in the television series? Critical Discourse Analysis is used as a tool that allows us to critically examine the image of diversity in children's stories. In light of the revision, an improvement is observed in the quantitative part, presenting a greater number of colored characters. It is estimated that media education would be the ideal strategy to develop the capacity for critical analysis of audiovisual content.Financiación: Ministerio de Educación Superior, Ciencia y Tecnología de la República Dominicana. Estudio de investigación asociado a un proyecto doctoral sobre la diversidad cultural en la televisión infantil

Deterministic polarization chaos from a laser diode

Fifty years after the invention of the laser diode and fourty years after the report of the butterfly effect - i.e. the unpredictability of deterministic chaos, it is said that a laser diode behaves like a damped nonlinear oscillator. Hence no chaos can be generated unless with additional forcing or parameter modulation. Here we report the first counter-example of a free-running laser diode generating chaos. The underlying physics is a nonlinear coupling between two elliptically polarized modes in a vertical-cavity surface-emitting laser. We identify chaos in experimental time-series and show theoretically the bifurcations leading to single- and double-scroll attractors with characteristics similar to Lorenz chaos. The reported polarization chaos resembles at first sight a noise-driven mode hopping but shows opposite statistical properties. Our findings open up new research areas that combine the high speed performances of microcavity lasers with controllable and integrated sources of optical chaos.Comment: 13 pages, 5 figure

Diversidad étnica en la televisión infantil: el caso de La Princesa Sofía

The media have become social prescribers. For this reason, it is increasingly important to examine how they draw and describe the social context, as well as how they represent the other. It is questioned how the representation of ethnic diversity is constructed in the television series? Critical Discourse Analysis is used as a tool that allows us to critically examine the image of diversity in children's stories. In light of the revision, an improvement is observed in the quantitative part, presenting a greater number of colored characters. It is estimated that media education would be the ideal strategy to develop the capacity for critical analysis of audiovisual content. Los medios de comunicación se han convertido en prescriptores sociales. Por ello es cada vez más importante examinar cómo estos dibujan y describen el contexto social, así como representan al otro. Problema de estudio: ¿cómo se construye la representación de la diversidad étnica en una serie infantil de televisión? Se hace uso del Análisis Crítico del Discurso como herramienta que permite examinar críticamente la imagen de la diversidad en el relato infantil. A la luz de la revisión se observa una mejora en la parte cuantitativa, presentando un mayor número de personajes de color. Se estima que la educación mediática es la estrategia idónea para desarrollar la capacidad de análisis crítico de los contenidos audiovisuales