Mode-coupling approach to non-Newtonian Hele-Shaw flow

The Saffman-Taylor viscous fingering problem is investigated for the displacement of a non-Newtonian fluid by a Newtonian one in a radial Hele-Shaw cell. We execute a mode-coupling approach to the problem and examine the morphology of the fluid-fluid interface in the weak shear limit. A differential equation describing the early nonlinear evolution of the interface modes is derived in detail. Owing to vorticity arising from our modified Darcy's law, we introduce a vector potential for the velocity in contrast to the conventional scalar potential. Our analytical results address how mode-coupling dynamics relates to tip-splitting and side branching in both shear thinning and shear thickening cases. The development of non-Newtonian interfacial patterns in rectangular Hele-Shaw cells is also analyzed.Comment: 14 pages, 5 ps figures, Revtex4, accepted for publication in Phys. Rev.

A phase-field model of Hele-Shaw flows in the high viscosity contrast regime

A one-sided phase-field model is proposed to study the dynamics of unstable interfaces of Hele-Shaw flows in the high viscosity contrast regime. The corresponding macroscopic equations are obtained by means of an asymptotic expansion from the phase-field model. Numerical integrations of the phase-field model in a rectangular Hele-Shaw cell reproduce finger competition with the final evolution to a steady state finger the width of which goes to one half of the channel width as the velocity increases

Viscous fingering in liquid crystals: Anisotropy and morphological transitions

We show that a minimal model for viscous fingering with a nematic liquid crystal in which anisotropy is considered to enter through two different viscosities in two perpendicular directions can be mapped to a two-fold anisotropy in the surface tension. We numerically integrate the dynamics of the resulting problem with the phase-field approach to find and characterize a transition between tip-splitting and side-branching as a function of both anisotropy and dimensionless surface tension. This anisotropy dependence could explain the experimentally observed (reentrant) transition as temperature and applied pressure are varied. Our observations are also consistent with previous experimental evidence in viscous fingering within an etched cell and simulations of solidification.Comment: 12 pages, 3 figures. Submitted to PR

Production of Bertholletia excelsa Humb. & Bonpl., (Lecythidaceae) seedlings in microenvironments under different substrates.

A falta de opções tecnológicas de concessionários de florestas para a produção de mudas de espécies nativas na Amazônia peruana é um gargalo para o reflorestamento na região. Neste estudo, uma nova tecnologia de produção de mudas de baixo custo e acessível a produtores foi desenvolvida. Assim, o objetivo neste trabalho foi avaliar a eficiência do uso de baldes como microambientes e substratos para o crescimento inicial de plântulas de Bertholletia excelsa. Aos 40 dias após a emergência, as plântulas foram repicadas para tubetes com capacidade de 115 cm³, contento um substrato padrão composto por areia + serragem + serragem carbonizada na proporção (1:1:1 v/v). Posteriormente, os tubetes foram acondicionadas em baldes (microambientes) com telado a 100% de sombra. O delineamento experimental foi inteiramente ao acaso e os tratamentos foram: T1 = areia, T2 = areia + serragem, T3 = casca de castanha decomposta e T4 = solo de floresta. O substrato T2 favoreceu o comprimento de parte aérea, raiz, número de folhas, massa seca da parte aérea, raízes e total, além do índice de esbeltez de mudas de B. excelsa. A qualidade das mudas de B. excelsa produzidas em microambientes foi semelhante entre os tratamentos, independente do substrato utilizado

Conservação genética e sua importância.

Este capítulo apresenta o estado da arte do conhecimento sobre diversidade genética e consanguinidade em populações adultas e regenerantes de castanheira-da-amazônia, com o intuito de discutir os riscos potenciais para as populações futuras.V. 4: Melhoramento genético e cultivo. ODS 2, ODS 3, ODS 8, ODS 11, ODS 12, ODS 13, ODS 17

CRISPR-enhanced human adipocyte \u27browning\u27 as cell therapy for metabolic disease [preprint]

Obesity and type 2 diabetes (T2D) are associated with poor tissue responses to insulin [1,2], disturbances in glucose and lipid fluxes [3-5] and comorbidities including steatohepatitis [6] and cardiovascular disease [7,8]. Despite extensive efforts at prevention and treatment [9,10], diabetes afflicts over 400 million people worldwide [11]. Whole body metabolism is regulated by adipose tissue depots [12-14], which include both lipid-storing white adipocytes and less abundant \u27brown\u27 and \u27brite/beige\u27 adipocytes that express thermogenic uncoupling protein UCP1 and secrete factors favorable to metabolic health [15-18]. Application of clustered regularly interspaced short palindromic repeats (CRISPR) gene editing [19,20] to enhance \u27browning\u27 of white adipose tissue is an attractive therapeutic approach to T2D. However, the problems of cell-selective delivery, immunogenicity of CRISPR reagents and long term stability of the modified adipocytes are formidable. To overcome these issues, we developed methods that deliver complexes of SpyCas9 protein and sgRNA ex vivo to disrupt the thermogenesis suppressor gene NRIP1 [21,22] with near 100% efficiency in human or mouse adipocytes. NRIP1 gene disruption at discrete loci strongly ablated NRIP1 protein and upregulated expression of UCP1 and beneficial secreted factors, while residual Cas9 protein and sgRNA were rapidly degraded. Implantation of the CRISPR-enhanced human or mouse brown-like adipocytes into high fat diet fed mice decreased adiposity and liver triglycerides while enhancing glucose tolerance compared to mice implanted with unmodified adipocytes. These findings advance a therapeutic strategy to improve metabolic homeostasis through CRISPR-based genetic modification of human adipocytes without exposure of the recipient to immunogenic Cas9 or delivery vectors

Effect of a Field-Source Mixture of Citrus Viroids on the Performance of Nules; Clementine and Navelina; Sweet Orange Trees Grafted on Carrizo Citrange

A field-source mixture of citrus viroids was characterized and shown to contain Citrus exocortis viroid (CEVd), Hop stunt viroid (HSVd), Citrus bent leaf viroid (CBLVd), and Citrus dwarfing viroid (CDVd). Sequencing results showed that: (i) CEVd contained the P(L) and P(R) characteristic of class A variants; (ii) HSVd was a noncachexia variant; (iii) CBLVd was related to CVd-Ia variants; (iv) CDVd was a mixture of two types (CVd-IIIa and CVd-IIIb) of variants. The presence of the same type of variants in inoculated clementine (Citrus clementina 'Nules') and sweet orange (C. sinensis 'Navelina') trees on Carrizo citrange (Poncirus trifoliata x C. sinensis) rootstocks was confirmed. The effect of infection was determined by assessing the performance of infected and noninfected trees growing in the field. Infection resulted in small trees with reduced canopy, yielding a reduced crop. Fruit characteristics were also affected: (i) clementine and sweet orange fruits from infected trees were larger than those from noninfected trees; (ii) clementine fruits from infected trees differed in shape from those of noninfected trees; (iii) sweet orange fruits from infected trees had maturity indexes and juice contents higher than those from noninfected trees; (iv) in both species, the density of the juice, the amount of soluble solids, and the acidity of the fruits from infected trees were lower than those of fruits from noninfected trees. Infected trees had a poorly developed root system with fibrous roots containing fewer amyloplasts than noninfected trees. The results of an in vitro assay on the induction and development of roots in cultured explants are discussed

Habitat quality differentiation and consequences for ecosystem service provision of an amazonian hyperdominant tree species.

Ecosystem services of Amazonian forests are disproportionally produced by a limited set of hyperdominant tree species. Yet the spatial variation in the delivery of ecosystem services by individual hyperdominant species across their distribution ranges and corresponding environmental gradients is poorly understood. Here, we use the concept of habitat quality to unravel the effect of environmental gradients on seed production and aboveground biomass (AGB) of the Brazil nut, one of Amazonia's largest and most long-lived hyperdominants. We find that a range of climate and soil gradients create trade-offs between density and fitness of Brazil nut trees. Density responses to environmental gradients were in line with predictions under the Janzen-Connell and Herms-Mattson hypotheses, whereas tree fitness responses were in line with resource requirements of trees over their life cycle. These trade-offs resulted in divergent responses in area-based seed production and AGB. While seed production and AGB of individual trees (i.e., fitness) responded similarly to most environmental gradients, they showed opposite tendencies to tree density for almost half of the gradients. However, for gradients creating opposite fitness-density responses, area-based seed production was invariable, while trends in area-based AGB tended to mirror the response of tree density. We conclude that while the relation between environmental gradients and tree density is generally indicative of the response of AGB accumulation in a given area of forest, this is not necessarily the case for fruit production