9,317 research outputs found

    Path regularity and explicit convergence rate for BSDE with truncated quadratic growth

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    We consider backward stochastic differential equations with drivers of quadratic growth (qgBSDE). We prove several statements concerning path regularity and stochastic smoothness of the solution processes of the qgBSDE, in particular we prove an extension of Zhang's path regularity theorem to the quadratic growth setting. We give explicit convergence rates for the difference between the solution of a qgBSDE and its truncation, filling an important gap in numerics for qgBSDE. We give an alternative proof of second order Malliavin differentiability for BSDE with drivers that are Lipschitz continuous (and differentiable), and then derive an analogous result for qgBSDE.Comment: 30 page

    FBSDEs with time delayed generators:L-P-solutions, differentiability, representation formulas and path regularity

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    AbstractWe extend the work of Delong and Imkeller (2010) [6,7] concerning backward stochastic differential equations with time delayed generators (delay BSDEs). We give moment and a priori estimates in general Lp-spaces and provide sufficient conditions for the solution of a delay BSDE to exist in Lp. We introduce decoupled systems of SDEs and delay BSDEs (delay FBSDEs) and give sufficient conditions for their variational differentiability. We connect these variational derivatives to the Malliavin derivatives of delay FBSDEs via the usual representation formulas. We conclude with several path regularity results, in particular we extend the classic L2-path regularity to delay FBSDEs

    Bougie

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    SummaryBackground and objectivesDifficult airways require fast action by the anesthesiologist often requiring complementary devices to ensure patent airways. However, several of those devices are expensive and require training in order to be used. The bougie, a simple and disposable device can also be manufactured by the anesthesiologist, making it a low cost tool.ContentsBougies are composed of one introducer that when inserted in the trachea helps orienting the introduction of the tracheal tube. It is a simple tool, easy to use, low in cost, and has been shown to be very useful in unexpected difficult airways.ConclusionsThe bougie has shown to be a valuable tool in the armamentarium of the anesthesiologist, and it is indicated in a wide range of situations

    Dynamic studies of biomimetic coated polycaprolactone nanofiber meshes as bone extracellular matrix analogues

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    This work aimed at studying the effects of dynamic culture conditions and biomimetic coating on bone cells grown on nanofiber meshes. In our previous work, biomimetic calcium phosphate coated polycaprolactone nanofibre meshes (BCP-NM) proved to be more efficient for supporting cell attachment and proliferation under static conditions, when compared to polycaprolactone nanofibre meshe (PCL-NM). However, no studies on the influence of bioreactors on the behaviour of cells cultivated on these materials were developed so far. [...]info:eu-repo/semantics/publishedVersio

    Synthesis and evaluation of novel bioactive composite starch/bioactive glass microparticles

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    The aim of the development of composite materials is to combine the most desired properties of two or more materials. In this work, the biodegradable character, good controlled-release properties, and natural origin of starch-based biomaterials are combined with the bioactive and bone-bonding properties of bioactive glass (BG). Novel, bioactive composite starch-BG microparticles were synthesized starting from a blend of starch and polylactic acid (50%/50% wt) with BG 45S5 powder using a simple emulsion method. Morphological and chemical characterization showed that these particles exhibited a spherical morphology with sizes up to 350 m and that BG 45S5 was incorporated successfully into the composite particles. Upon immersion in a solution simulating body fluids, for periods up to 3 weeks, their bioactive nature was confirmed, as a calcium-phosphate layer resembling biological apatite was formed onto their surface. The short-term cytotoxicity of these materials was also tested by placing 24-h leachables of the materials extracted in culture medium in contact with a fibroblastic cell line (L929) up to 72 h. At this time period, two biochemical tests - MTT and total protein quantification - were performed. The results showed that these materials are not cytotoxic. These results constitute the basis of future encapsulation studies using bone-acting therapeutic agents such as bone morphogenetic proteins or other bone-relevant factors. The particles developed here may be very useful for applications in which controlled release, degradability, and bone-bonding ability are the main requirements.FCT Foundation for Science and Technology, through funds from the POCTI and/or FEDER programmes

    El cotidiano de mujeres embarazadas em el hogar de una maternidad social

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    Estudo realizado em uma instituição que oferece moradia e atendimento à saúde para gestantes em situação de vulnerabilidade social. O objetivo foi compreender como as mulheres vivenciam o processo gravídico, morando nessa instituição. Em 2006, realizou-se entrevista semi-estruturada com 10 mulheres. Os depoimentos foram analisados, utilizando-se a fenomenologia social. Pela análise das categorias, compreendeu-se o tipo vivido: mulheres no processo gravídico, morando em uma instituição social e de saúde, como aquele grupo que, buscando soluções, procurou acolhimento e mudanças na condição de vida; no dia-a-dia no alojamento, convivendo positiva e negativamente com a experiência do outro, julgando-se em casa, mas também sentindo solidão, privação da liberdade e percebendo possibilidades de aprendizado. Após esta experiência, as mulheres pretendem retornar ao cotidiano com novos projetos. Mostra a importância da instituição para atenuar a angústia e as incertezas que influenciam os indicadores de saúde e proporcionar condição para reintegração social.This study was carried out in an institution that offers lodging and health assistance for pregnant women in at-risk social situations. Its purpose was to better understand how women live pregnancy while they live in this institution. In 2006, 10 women participated in semi-structured interviews. The women's depositions were analyzed by the social phenomenology theoretical framework. Through category analysis, the lived types were classified as: women who lived the pregnancy living in a social and health care institution; as the social group which, searching for solutions, sought shelter and changes in their life conditions; lived their daily lives at the institution, coexisting negatively and positively with the experience of the other; judged themselves to be at home, but also felt solitude, freedom deprivation, and perceived learning possibilities. After this experience, they intended to return to their daily lives in new projects. The results disclosed the importance of the institution in order to attenuate affliction and the uncertainties that can influence biological health indicators, as well as to provide conditions for social reintegration.Investigación realizada en una institución que ofrece hospedaje y atención de salud para mujeres embarazadas en situación de vulnerabilidad social. El objetivo fue comprender cómo vivencian las mujeres el proceso del embarazo, al vivir en esa institución. En el año de 2006 se realizó una entrevista parcialmente elaborada con diez mujeres. Los discursos fueron analizados según el referencial de la fenomenología social. Por el análisis de las categorías se comprendió el proceso vivenciado por las mujeres alojadas en una institución social y de salud, como aquel grupo que, buscando soluciones, procura acogida y cambio en su condición de vida, vive el cotidiano en el alojamiento, conviviendo positiva y negativamente con la experiencia del otro, sintiéndose como en casa, pero experimentando también soledad, privación de su libertad y percibiendo posibilidades de aprendizaje. Después de vivir esta experiencia, pretenden retornar al cotidiano con nuevos proyectos de vida. Se mostró la importancia que tiene la institución para atenuar la angustia y la incertidumbre que influye en los indicadores de salud y proporciona condición para la reintegración social

    Crossover effects in a discrete deposition model with Kardar-Parisi-Zhang scaling

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    We simulated a growth model in 1+1 dimensions in which particles are aggregated according to the rules of ballistic deposition with probability p or according to the rules of random deposition with surface relaxation (Family model) with probability 1-p. For any p>0, this system is in the Kardar-Parisi-Zhang (KPZ) universality class, but it presents a slow crossover from the Edwards-Wilkinson class (EW) for small p. From the scaling of the growth velocity, the parameter p is connected to the coefficient of the nonlinear term of the KPZ equation, lambda, giving lambda ~ p^gamma, with gamma = 2.1 +- 0.2. Our numerical results confirm the interface width scaling in the growth regime as W ~ lambda^beta t^beta, and the scaling of the saturation time as tau ~ lambda^(-1) L^z, with the expected exponents beta =1/3 and z=3/2 and strong corrections to scaling for small lambda. This picture is consistent with a crossover time from EW to KPZ growth in the form t_c ~ lambda^(-4) ~ p^(-8), in agreement with scaling theories and renormalization group analysis. Some consequences of the slow crossover in this problem are discussed and may help investigations of more complex models.Comment: 16 pages, 7 figures; to appear in Phys. Rev.

    Dynamic culture of osteogenic cells in biomimetically coated poly(caprolactone) nanofibre mesh constructs

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    In our previous work, biomimetic calcium phosphate-coated poly(caprolactone) nanofibre meshes (BCP-NMs) were demonstrated to be more effective for supporting cell attachment and proliferation under static conditions, when compared with poly(caprolactone) nanofibre meshes (PCL-NMs). In many applications, in vitro cultivation of constructs using bioreactors that support efficient nutrition of cells has appeared as an important step toward the development of functional grafts. This work aimed at studying the effects of dynamic culture conditions and biomimetic coating on bone cells grown on the nanofibre meshes. BCP-NM and PCL-NM were seeded with osteoblast-like cells (MG63--human osteosarcoma-derived cell line). The cell-seeded constructs were cultured within a rotating bioreactor that simulated microgravity, at a fixed rotating speed, for different time periods, and then characterized. Cell morphology, viability, and phenotype were assessed. PCL-NM constructs presented a higher number of dead cells than BCP-NM constructs. Under dynamic conditions, the production of proteins associated with the extracellular matrix of bone was higher on BCP-NM constructs than in the PCL-NM ones, which indicates that coated samples may provide cells with a better environment for tissue growth. It is suggested that improved mass transfer in the bioreactor in combination with the appropriate substrate were decisive factors for this highly positive outcome for generating bone.This work was developed under the scope of the EU Project Network of Excellence "Expertissues'' (NMP3-CT-2004-500283) and supported by Alea jacta est Marie Curie Actions (MEST-CT-2004-008104). M. Alves da Silva would like to acknowledge the Portuguese Foundation for Science and Technology for her grant (SFRH-BD-28708-2006). Jose V. Araujo is grateful to S. Rathbone, H. Sura, I. Wimpenny, I. Dublon, G. Jones, and E. D. Pinho for useful technical discussions

    Effect of inoculation with Azospirillum and Herbaspirillum on production of indolic compounds and growth of wheat and rice seedlings

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    Bactérias fixadoras de nitrogênio podem contribuir para o crescimento vegetal pela produção de auxinas. Os objetivos deste trabalho foram quantificar a produção de hormônios de crescimento por estirpes de bactérias fixadoras de nitrogênio e avaliar o efeito da inoculação destas estirpes em plântulas de milho e trigo. Todas as estirpes avaliadas começaram a produzir indóis no final da fase logarítmica. Houve efeito da adição de diferentes concentrações de triptofano ao meio de cultivo no aumento da produção de indóis até o nível de 200 µM. Nas estirpes de Azospirillum, as formas de N: NH4Cl, (NH4)2SO4, NH4H2PO4 e NH4NO3 estimularam a produção de indóis em níveis baixos. A adição de KNO3, NaNO3 e KNO2 inibiu a produção de indóis em todas as bactérias testadas e no crescimento de células de Azospirillum. Os efeitos da inoculação foram também comparados com concentrações crescentes do ácido 3-indolacético, KNO3 e triptofano. Em condições axênicas, a elevada produção de indóis reduz o comprimento das raízes e colmos na presença de triptofano, especialmente quando submetidas à inoculação de Azospirillum.Nitrogen fixing bacteria can contribute to plant growth by the production of auxin. The objectives of this work were to quantify the production of plant growth hormones by different nitrogen-fixing bacteria and to evaluate the effect of this inoculation on growth of wheat and rice seedlings. All strains tested produced indoles during the late logarithmic phase. Increasing the amount of tryptophan in the medium enhanced the production of indoles by the bacteria up to the level of 200 µM. For the Azospirillum strains studied, the nitrogen sources: NH4Cl, (NH4)2SO4, NH4H2PO4 and NH4NO3 stimulated indoles production in low levels. The addition of KNO3, NaNO3 and KNO2 inhibited the production of indole compounds for all bacteria tested as well as the Azospirillum growth. The effects of inoculation were also compared to those caused by increased concentrations of IAA, KNO3 and tryptophan alone. In vitro conditions, the high amounts of indoles produced by the bacteria reduce the length of roots and stems in the presence of tryptophan, especially in the case of Azospirillum strains
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