91 research outputs found

    Alliance free sets in Cartesian product graphs

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    Let G=(V,E)G=(V,E) be a graph. For a non-empty subset of vertices SVS\subseteq V, and vertex vVv\in V, let δS(v)={uS:uvE}\delta_S(v)=|\{u\in S:uv\in E\}| denote the cardinality of the set of neighbors of vv in SS, and let Sˉ=VS\bar{S}=V-S. Consider the following condition: {equation}\label{alliancecondition} \delta_S(v)\ge \delta_{\bar{S}}(v)+k, \{equation} which states that a vertex vv has at least kk more neighbors in SS than it has in Sˉ\bar{S}. A set SVS\subseteq V that satisfies Condition (\ref{alliancecondition}) for every vertex vSv \in S is called a \emph{defensive} kk-\emph{alliance}; for every vertex vv in the neighborhood of SS is called an \emph{offensive} kk-\emph{alliance}. A subset of vertices SVS\subseteq V, is a \emph{powerful} kk-\emph{alliance} if it is both a defensive kk-alliance and an offensive (k+2)(k +2)-alliance. Moreover, a subset XVX\subset V is a defensive (an offensive or a powerful) kk-alliance free set if XX does not contain any defensive (offensive or powerful, respectively) kk-alliance. In this article we study the relationships between defensive (offensive, powerful) kk-alliance free sets in Cartesian product graphs and defensive (offensive, powerful) kk-alliance free sets in the factor graphs

    Material flow analysis in indentation process by 3D Digital Image Correlation

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    Focusing in the application of the 3D Digital Image Correlation technique, this work proposes a material flow analysis in an indentation process. The study establishes the methodology for the calibration and implementation of the 3D image sensing technology for deformation measurements. The purpose is to continue with the validation of the DIC application to the indentation processes, where a deep penetration is achieved and extensive material flow is produced. With the 3D DIC technique is possible to perform accurate deformation measurements in not planar specimens and study the material emerging towards the exterior of the tested specimen, which is not possible with the 2D DIC technique. Although previous 2D studies were efficient detecting the flow field and von Mises strains on the specimens tested, the bulge emerging under the punch on the front surface (dead zone) could not be studied due to its predominantly 3D character. Therefore, present work implements a 3D methodology that carries out a complete study of the deformation, including the material flow that occurs on the Z axis, towards the exterior of the tested specimen, optimizing previous analyses.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Myosin light-chain phosphatase regulates basal actomyosin oscillations during morphogenesis

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    Contractile actomyosin networks generate forces that drive tissue morphogenesis. Actomyosin contractility is controlled primarily by reversible phosphorylation of the myosin-II regulatory light chain through the action of myosin kinases and phosphatases. While the role of myosin light-chain kinase in regulating contractility during morphogenesis has been largely characterized, there is surprisingly little information on myosin light-chain phosphatase (MLCP) function in this context. Here, we use live imaging of Drosophila follicle cells combined with mathematical modelling to demonstrate that the MLCP subunit flapwing (flw) is a key regulator of basal myosin oscillations and cell contractions underlying egg chamber elongation. Flw expression decreases specifically on the basal side of follicle cells at the onset of contraction and flw controls the initiation and periodicity of basal actomyosin oscillations. Contrary to previous reports, basal F-actin pulsates similarly to myosin. Finally, we propose a quantitative model in which periodic basal actomyosin oscillations arise in a cell-autonomous fashion from intrinsic properties of motor assembliesResearch in our laboratories is funded by the Spanish Ministerio de Economía y Competitividad and the FEDER programme (BFU2013-48988-C2-1-P to M.D.M.-B, BFU2012-35446 to A.G.-R., BFU2011-30303 and BFU2010-18959 to D.G.M.) and by the Junta de Andalucía (Proyecto de Excelencia P09-CVI-5058). I.G. was supported by a JAE-DOC (CSIC) and D.G.M. by a Ramon y Cajal Fellowship (Ministerio Español de Economía y Competitividad Ref. RYC-2010-07450) and a Marie Curie International Reintegration Grant (EU, Ref. 248346-NMSSBLS

    Alliance free and alliance cover sets

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    A \emph{defensive} (\emph{offensive}) kk-\emph{alliance} in Γ=(V,E)\Gamma=(V,E) is a set SVS\subseteq V such that every vv in SS (in the boundary of SS) has at least kk more neighbors in SS than it has in VSV\setminus S. A set XVX\subseteq V is \emph{defensive} (\emph{offensive}) kk-\emph{alliance free,} if for all defensive (offensive) kk-alliance SS, SXS\setminus X\neq\emptyset, i.e., XX does not contain any defensive (offensive) kk-alliance as a subset. A set YVY \subseteq V is a \emph{defensive} (\emph{offensive}) kk-\emph{alliance cover}, if for all defensive (offensive) kk-alliance SS, SYS\cap Y\neq\emptyset, i.e., YY contains at least one vertex from each defensive (offensive) kk-alliance of Γ\Gamma. In this paper we show several mathematical properties of defensive (offensive) kk-alliance free sets and defensive (offensive) kk-alliance cover sets, including tight bounds on the cardinality of defensive (offensive) kk-alliance free (cover) sets

    Carotenoids from persimmon juice processing

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    [EN] The aim of this study was the use and revalorization of two persimmon by-products A and B generated in the juice production process. The by-product B resulting from a pectinase enzymatic treatment of peels and pulp to optimize juice extraction was especially suitable for recovery of valuable bioactive carotenoids. The extraction solvents and solvent combinations used were: ethanol, acetone, ethanol/acetone (50:50 v/v) and ethanol/ acetone/hexane (25:25:50 v/v/v). HPLC-DAD analysis detected and identified a total of nine individual carotenoids namely violaxanthin, neoxanthin, antheraxanthin, lutein, zeaxanthin, ß-cryptoxanthin 5,6-epoxide, ß-cryptoxanthin, ¿-carotene, and ß-carotene. ß-cryptoxanthin and ß-carotene represented 49.2% and 13.2% of the total carotenoid content (TCC) in the acetone extract from by-product B. TCC contributed greatly to antioxidant activity of acetone extract derived from this by-product. Pectinase enzymatic treatment of persimmon peels and pulp followed by absolute acetone extraction of carotenoids could be an efficient method to obtain a rich extract in these compounds that could be used as nutraceutical ingredient.This study was supported by Ministerio de Ciencia, Innovacion y Universidades through the funded project 'Simbiosis industrial en el aprovechamiento integral del caqui (Diospyros kaki); Ejemplo de bioeconomia' (CTM2017-88978-R). Sara Gea-Botella thanks the Agencia Estatal de Investigacion la Ayuda para la Formacion de Doctores en Empresas "Doctorados Industriales" (DI-16-08465) through the R+D+i project entitled 'Evaluacion in vitro e in vivo de un extracto procedente de subproductos de la industrializacion del caqui'. The authors wish to thank Mitra Sol Technologies S.L. the given technical assistance.Gea-Botella, S.; Agulló, L.; Martí, N.; Martínez-Madrid, M.; Lizama Abad, V.; Martín-Bermudo, F.; Berná, G.... (2021). Carotenoids from persimmon juice processing. Food Research International. 141:1-8. https://doi.org/10.1016/j.foodres.2020.109882S1814

    PS Integrins and Laminins: Key Regulators of Cell Migration during Drosophila Embryogenesis

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    During embryonic development, there are numerous cases where organ or tissue formation depends upon the migration of primordial cells. In the Drosophila embryo, the visceral mesoderm (vm) acts as a substrate for the migration of several cell populations of epithelial origin, including the endoderm, the trachea and the salivary glands. These migratory processes require both integrins and laminins. The current model is that αPS1βPS (PS1) and/or αPS3βPS (PS3) integrins are required in migrating cells, whereas αPS2βPS (PS2) integrin is required in the vm, where it performs an as yet unidentified function. Here, we show that PS1 integrins are also required for the migration over the vm of cells of mesodermal origin, the caudal visceral mesoderm (CVM). These results support a model in which PS1 might have evolved to acquire the migratory function of integrins, irrespective of the origin of the tissue. This integrin function is highly specific and its specificity resides mainly in the extracellular domain. In addition, we have identified the Laminin α1,2 trimer, as the key extracellular matrix (ECM) component regulating CVM migration. Furthermore, we show that, as it is the case in vertebrates, integrins, and specifically PS2, contributes to CVM movement by participating in the correct assembly of the ECM that serves as tracks for migration

    Patient Reported Experiences and Delays During the Diagnostic Pathway for Pulmonary Fibrosis: A Multinational European Survey.

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    Introduction: Pulmonary fibrosis includes a spectrum of diseases and is incurable. There is a variation in disease course, but it is often progressive leading to increased breathlessness, impaired quality of life, and decreased life expectancy. Detection of pulmonary fibrosis is challenging, which contributes to considerable delays in diagnosis and treatment. More knowledge about the diagnostic journey from patients' perspective is needed to improve the diagnostic pathway. The aims of this study were to evaluate the time to diagnosis of pulmonary fibrosis, identify potential reasons for delays, and document patients emotions. Methods: Members of European patient organisations, with a self-reported diagnosis of pulmonary fibrosis, were invited to participate in an online survey. The survey assessed the diagnostic pathway retrospectively, focusing on four stages: (1) time from initial symptoms to first appointment in primary care; (2) time to hospital referral; (3) time to first hospital appointment; (4) time to final diagnosis. It comprised open-ended and closed questions focusing on time to diagnosis, factors contributing to delays, diagnostic tests, patient emotions, and information provision. Results: Two hundred and seventy three participants (214 idiopathic pulmonary fibrosis, 28 sarcoidosis, 31 other) from 13 countries responded. Forty percent of individuals took ≥1 year to receive a final diagnosis. Greatest delays were reported in stage 1, with only 50.2% making an appointment within 3 months. For stage 2, 73.3% reported a hospital referral within three primary care visits. However, 9.9% reported six or more visits. After referral, 76.9% of patients were assessed by a specialist within 3 months (stage 3) and 62.6% received a final diagnosis within 3 months of their first hospital visit (stage 4). Emotions during the journey were overall negative. A major need for more information and support during and after the diagnostic process was identified. Conclusion: The time to diagnose pulmonary fibrosis varies widely across Europe. Delays occur at each stage of the diagnostic pathway. Raising awareness about pulmonary fibrosis amongst the general population and healthcare workers is essential to shorten the time to diagnosis. Furthermore, there remains a need to provide patients with sufficient information and support at all stages of their diagnostic journey

    Integrin-mediated axoglial interactions initiate myelination in the central nervous system

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    All but the smallest-diameter axons in the central nervous system are myelinated, but the signals that initiate myelination are unknown. Our prior work has shown that integrin signaling forms part of the cell–cell interactions that ensure only those oligodendrocytes contacting axons survive. Here, therefore, we have asked whether integrins regulate the interactions that lead to myelination. Using homologous recombination to insert a single-copy transgene into the hypoxanthine phosphoribosyl transferase (hprt) locus, we find that mice expressing a dominant-negative β1 integrin in myelinating oligodendrocytes require a larger axon diameter to initiate timely myelination. Mice with a conditional deletion of focal adhesion kinase (a signaling molecule activated by integrins) exhibit a similar phenotype. Conversely, transgenic mice expressing dominant-negative β3 integrin in oligodendrocytes display no myelination abnormalities. We conclude that β1 integrin plays a key role in the axoglial interactions that sense axon size and initiate myelination, such that loss of integrin signaling leads to a delay in myelination of small-diameter axons
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