Characterization of the killer toxin KTCf20 from wickerhamomyces anomalus, a potential biocontrol agent against wine spoilage yeasts

Wickerhamomyces anomalus Cf20 secretes the killer toxin KTCf20 that inhibits several wine spoilage yeasts of the species Pichia guilliermondii, P. membranifaciens, Brettanomyces bruxellensis and Dekkera anomala. KTCf20 binds cell wall extracts from the sensitive target P. guilliermondii Cd6; however, this capacity was lost when cell wall extracts were pre-treated with fungal β-glucanase. Pustulan and laminarin inhibited killer activity, suggesting that β-1,3 and β-1,6-glucans may be the putative binding sites for KTCf20 on the cell wall of sensitive cells. The toxin was produced and showed to be stable and highly active at physicochemical conditions suitable for winemaking process. In addition, the strain Cf20 is compatible with Saccharomyces cerevisiae in co-culture conditions being potential its application in a mixed starter culture. These data suggest that W. anomalus Cf20 and/or KTCf20 are promising biocontrol agents against spoilage yeasts during wine-making process.Fil: Fernandez de Ullivarri, Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Mendoza, Lucia Margarita. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Raya, Raul Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentin

Strength of pile caps under eccentric loads: Experimental study and review of code provisions

[EN] Pile caps are rigid reinforced concrete structures that transfer column loads, generally consisting of a combination of an axial load and bending moments in one or two directions, to the piles. The design formulations of pile caps for more than two piles were derived from the results of experimental tests under a centered load. The practice of checking both punching and shear failure modes is common as described in the literature review, even though these formulations were developed for more slender elements. Currently, Codes ACI 318-14 and EC2 allow designing pile caps with strut-and-tie models or sectional approaches (shear, punching and flexural designs). In this study, 21 full-scale pile caps with different shear span-depth ratios and reinforcement layouts were studied to investigate the effect of eccentric loading on the strength and accuracy of the code formulations. The results show that in eccentrically loaded pile caps, the ultimate load is reduced but the maximum pile reaction increases and the secondary reinforcement proves effective to enhance the pile cap strength. Although the strut-and-tie models (STM) allow eccentric loads to be taken into consideration, they predict a much lower peak load than that observed at the experimental results and do not adequately reflect either the influence of slenderness or the failure mode. In general the sectional approach provided by Codes ACI-318-14, EC2 and MC-2010 (Level I of Approximation) lead to safe predictions of the peak load but do not always correctly predict the failure mode. The ultimate load predicted by EC-2 formulation comes closest to the experimental peak load, accurately reflects the influence of slenderness and the effect of secondary reinforcement, however, additional assumptions need to be made for its application. The ACI formulation complemented by the CRSI-2008 Special Investigation for deep pile caps is the safest but does not adequately capture the effect of horizontal and vertical secondary reinforcement. The MC2010 LoAI formulation is also conservative but does not detect the influence of slenderness or the contribution of secondary reinforcement.The authors wish to express their gratitude for the financial support (BIA2012-32300 and BIA2015-64672-C4-4-R) received from the Spanish Ministry of Economy and Competitiveness, which enabled the experimental campaign to be carried out, also for the PhD fellowship (BES-2013-063409).Miguel-Tortola, L.; Miguel Sosa, P.; Pallarés Rubio, L. (2019). Strength of pile caps under eccentric loads: Experimental study and review of code provisions. Engineering Structures. 182:251-267. https://doi.org/10.1016/j.engstruct.2018.12.064S25126718

Punching shear failure in three-pile caps: Influence of the shear span-depth ratio and secondary reinforcement

[EN] The strut-and-tie model (STM) is currently established as the best approach for pile cap design. This model leads to efficient estimations of the main reinforcement placed in strips between piles. However, good practices and some international Concrete Design Standards recommend some secondary distributed reinforcement, and even vertical stirrups that are not considered by the STM. An experimental campaign with nine three-pile caps tested by a centered load is presented to show the influence of both secondary reinforcement and the shear span-depth ratio on pile cap strength. The experimental results show a potential redistribution of internal forces in pile caps after yielding of main reinforcement, finally collapsed due to punching. Secondary reinforcement proves efficient to enhance pile cap strength since it takes part in complementary resistance mechanisms. As expected, the failure load increases with shear span-depth ratio reduction. The STM neither captures the effect of this ratio nor considers punching failure. Checking this failure mode is also required for pile caps. The punching formulation of Eurocode 2 allows considering the influence of this ratio, but some interpretation is required whether one deals with pile caps, regarding the effective width of the shear enhancement factor and the definition of the basic control perimeter. A proper definition would prevent unsafe or very conservative results. Therefore, some recommendations for the verification of deep pile caps following the Eurocode 2 are presented. The contribution of vertical stirrups as punching reinforcement is also investigated. The proposed approach is applied to the existing experimental database of three- and four-pile caps to check formulation validity, and conservative predictions with low coefficient of variation are reached.The authors would like to acknowledge the funding received from the Spanish Ministry of Economy and Competitiveness for basic non oriented research projects (BIA2012-32300), which also included a PhD fellowship (BES-2013-063409).Miguel-Tortola, L.; Pallarés Rubio, L.; Miguel Sosa, P. (2018). Punching shear failure in three-pile caps: Influence of the shear span-depth ratio and secondary reinforcement. Engineering Structures. 155:127-142. https://doi.org/10.1016/j.engstruct.2017.10.077S12714215

Density-based mixing parameter for hybrid functionals

A very popular ab-initio scheme to calculate electronic properties in solids is the use of hybrid functionals in density functional theory (DFT) that mixes a portion of Fock exchange with DFT functionals. In spite of their success, a major problem still remains, related to the use of one single mixing parameter for all materials. Guided by physical arguments that connect the mixing parameter to the dielectric properties of the solid, and ultimately to its band gap, we propose a method to calculate this parameter from the electronic density alone. This method is able to cut significantly the error of traditional hybrid functionals for large and small gap materials, while retaining a good description of structural properties. Moreover, its implementation is simple and leads to a negligible increase of the computational time.Comment: submitte

Modeling tumorspheres reveals cancer stem cell niche building and plasticity

Cancer stem cells have been shown to be critical to the development of a variety of solid cancers. The precise interplay mechanisms between cancer stem cells and the rest of a tissue are still not elucidated. To shed light on the interactions between stem and non-stem cancer cell populations we develop a two-population mathematical model, which is suitable to describe tumorsphere growth. Both interspecific and intraspecific interactions, mediated by the microenvironment, are included. We show that there is a tipping point, characterized by a transcritical bifurcation, where a purely non-stem cell attractor is replaced by a new attractor that contains both stem and differentiated cancer cells. The model is then applied to describe the outcome of a recent experiment. This description reveals that, while the intraspecific interactions are inhibitory, the interspecific interactions stimulate growth. This can be understood in terms of stem cells needing differentiated cells to reinforce their niches, and phenotypic plasticity favoring the de-differentiation of differentiated cells into cancer stem cells. We posit that this is a consequence of the deregulation of the quorum sensing that maintains homeostasis in healthy tissues.Fil: Benitez, Lucia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; ArgentinaFil: Barberis, Lucas Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; ArgentinaFil: Condat, Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentin

Estimation of the Contaminant Risk Level of Petroleum Residues Applying FDA Techniques

In the process of oil extraction, specifically in therefinement and industrialization of hydrocarbons, as is known,multiple wastes are highly polluting for the soil, water and air.In this work, the risk level of these wastes in affected areasis estimated thanks to the application of statistical models inthe field of functional data analysis. These models have beenimplemented in a statistical software called RStudio that allowsan early measurement and evaluation of the level of risk by usingsemiquantitative and quantitative methods. This measurement iscarried out by the staff of PETROECUADOR close to the affectedplace. It was used the laser-induced fluorescence technique (LIF).The data obtained using this technique was used to adjust thefollowing models: Generalized Functional Linear Model (MLFG),which makes it possible to classify the spectrum generated intwo pollution levels: Low and High. Functional linear regressionmodel with scalar response and functional explanatory variablewith the aim of directly estimating the percentage of contaminationlevel. With these results it is verified that the shape ofthe laser fluorescence spectrum is highly related to the gasolinecontent in the sample. &nbsp

Local and global ordering dynamics in multi-state voter models

We investigate the time evolution of the density of active links and of the entropy of the distribution of agents among opinions in multi-state voter models with all-to-all interaction and on uncorrelated networks. Individual realisations undergo a sequence of eliminations of opinions until consensus is reached. After each elimination the population remains in a meta-stable state. The density of active links and the entropy in these states varies from realisation to realisation. Making some simple assumptions we are able to analytically calculate the average density of active links and the average entropy in each of these states. We also show that, averaged over realisations, the density of active links decays exponentially, with a time scale set by the size and geometry of the graph, but independent of the initial number of opinion states. The decay of the average entropy is exponential only at long times when there are at most two opinions left in the population. Finally, we show how meta-stable states comprised of only a subset of opinions can be artificially engineered by introducing precisely one zealot in each of the prevailing opinions.Comment: 18 pages, 18 figure

Rentabilidad de los fondos de inversión en España. (1991-2006)

En los últimos cinco y diez años, la rentabilidad promedio de los fondos de inversión fue inferior a la inflación. A pesar de estos resultados, el 31 de diciembre de 2006, 8.819.809 partícipes tenían un patrimonio de 254.306 millones de euros en los 2.779 fondos de inversión existentes. En 2006 se lanzaron al mercado 246 nuevos fondos. Sólo 23 de los 649 fondos con diez años de historia han obtenido una rentabilidad superior al benchmark utilizado. Por ejemplo, de los 43 fondos de "renta variable nacional" con diez años de historia, sólo uno consiguió una rentabilidad superior a la del Indice Total de la Bolsa de Madrid. Si la rentabilidad de cada fondo de inversión en los últimos cinco años no hubiera sido la realmente obtenida, sino el benchmark de su categoría, la apreciación de los fondos en el período 2002-2006 habría sido 67.768 millones de euros en lugar de los 28.013 millones que obtuvieron. El total de comisiones y gastos repercutidos en este período ascendió a 12.805 millones de euros.fondos de inversión; rentabilidad partícipes; benchmark; apreciación fondos;

Rentabilidad de los fondos de inversión de renta variable nacional en España (1991-2006)

La rentabilidad media de los fondos de inversión en renta variable nacional durante los tres, cinco, diez y quince últimos años fue inferior a la del ITBM (Indice Total de la Bolsa de Madrid) en más de un 6%. De los 43 fondos con diez años de historia, sólo uno (Bestinver Bolsa, que hizo honor a su nombre) consiguió una rentabilidad superior a la del ITBM. Veinticuatro de estos fondos tuvieron todos los años una rentabilidad inferior a la del ITBM. Sólo dos de los 99 fondos con tres años de historia consiguieron una rentabilidad superior al ITBM (Bestinver Bolsa y Metavalor). Si la rentabilidad de cada fondo de inversión en los últimos quince años no hubiera sido la realmente obtenida, sino la del ITBM, la apreciación de los fondos en el período 1991-2006 habría sido de 13.753 millones de euros en lugar de los 6.480 millones de euros que obtuvieron. El total de comisiones y gastos repercutidos en este período ascendió a unos 1.400 millones de euros. El resto se debe a comisiones ocultas y a decisiones de inversión mejorables.fondos de inversión; rentabilidad partícipes; benchmark; apreciación fondos;

Understanding the influence of substrate when growing tumorspheres

Background: Cancer stem cells are important for the development of many solid tumors. These cells receive promoting and inhibitory signals that depend on the nature of their environment (their niche) and determine cell dynamics. Mechanical stresses are crucial to the initiation and interpretation of these signals. Methods: A two-population mathematical model of tumorsphere growth is used to interpret the results of a series of experiments recently carried out in Tianjin, China, and extract information about the intraspecific and interspecific interactions between cancer stem cell and differentiated cancer cell populations. Results: The model allows us to reconstruct the time evolution of the cancer stem cell fraction, which was not directly measured. We find that, in the presence of stem cell growth factors, the interspecific cooperation between cancer stem cells and differentiated cancer cells induces a positive feedback loop that determines growth, independently of substrate hardness. In a frustrated attempt to reconstitute the stem cell niche, the number of cancer stem cells increases continuously with a reproduction rate that is enhanced by a hard substrate. For growth on soft agar, intraspecific interactions are always inhibitory, but on hard agar the interactions between stem cells are collaborative while those between differentiated cells are strongly inhibitory. Evidence also suggests that a hard substrate brings about a large fraction of asymmetric stem cell divisions. In the absence of stem cell growth factors, the barrier to differentiation is broken and overall growth is faster, even if the stem cell number is conserved. Conclusions: Our interpretation of the experimental results validates the centrality of the concept of stem cell niche when tumor growth is fueled by cancer stem cells. Niche memory is found to be responsible for the characteristic population dynamics observed in tumorspheres. The model also shows why substratum stiffness has a deep influence on the behavior of cancer stem cells, stiffer substrates leading to a larger proportion of asymmetric doublings. A specific condition for the growth of the cancer stem cell number is also obtainedFil: Benitez, Lucia. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Barberis, Lucas Miguel. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Vellón, Luciano. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Condat, Carlos. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentin