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The lifting Hele-Shaw cell flow commonly involves the stretching of a viscous oil droplet surrounded by air, in the confined space between two parallel plates. As the upper plate is lifted, viscous fingering instabilities emerge at the air-oil interface. Such an interfacial instability phenomenon is widely observed in numerous technological and industrial applications, being quite difficult to control. Motivated by the recent interest in controlling and stabilizing the Saffman-Taylor instability in lifting Hele-Shaw flows, we propose an alternative way to restrain the development of interfacial disturbances in this gap-variable system. Our method modifies the traditional plate-lifting flow arrangement by introducing a finite fluid annulus layer encircling the central oil droplet, and separating it from the air. A second-order, perturbative mode-coupling approach is employed to analyze morphological and stability behaviors in this three-fluid, two-interface, doubly connected system. Our findings indicate that the intermediate fluid ring can significantly stabilize the interface of the central oil droplet. We show that the effectiveness of this stabilization protocol relies on the appropriate choice of the ring's viscosity and thickness. Furthermore, we calculate the adhesion force required to detach the plates, and find that it does not change significantly with the addition of the fluid envelope as long as it is sufficiently thin. Finally, we detect no distinction in the adhesion force computed for stable or unstable annular interfaces, indicating that the presence of fingering at the ring's boundaries has a negligible effect on the adhesion force.

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Leishmania (L.) amazonensis is one of the species responsible for the development of cutaneous leishmaniasis in South America. After entering the vertebrate host, L. (L.) amazonensis invades mainly neutrophils, macrophages and dendritic cells. Studies have shown that gal-3 acts as a pattern recognition receptor. However, the role of this protein in the context of L. (L.) amazonensis infection remains unclear. Here, we investigated the impact of gal-3 expression on experimental infection by L. (L.) amazonensis. Our data showed that gal-3 plays a role in controlling parasite invasion, replication and the formation of endocytic vesicles. Moreover, mice with gal-3 deficiency showed an exacerbated inflammatory response. Taken together, our data shed light to a critical role of gal-3 in the host response to infection by L. (L.) amazonensis.

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We analyze the morphology and dynamic behavior of the interface separating a ferrofluid and a nonmagnetic fluid in a Hele-Shaw cell, when crossed radial and azimuthal magnetic fields are applied. In addition to inducing the formation of a variety of eye-catching, complex interfacial structures, the action of the crossed fields makes the deformed ferrofluid droplet to rotate. Numerical simulations and perturbative mode-coupling theory are employed to look into early linear, intermediate weakly nonlinear, and fully nonlinear dynamic regimes of the pattern-forming process. We investigate how the system responds to variations in the viscosity difference between the fluids, the magnetic susceptibility of the ferrofluid, the effects of surface tension, and in the relative strength between radial and azimuthal applied magnetic fields. The role played by random perturbations at the initial conditions in determining the ultimate shape and dynamic stability of the spinning ferrofluid patterns is also studied.

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The main purpose of this paper was to present the Forestry Routing Optimization Model (FRoM) as a version of the classical Vehicle Routing Problem (VRP). This work approaches for wood logistic problems consisting of simple displacement and multiple displacements of trucks toward the stands. The FRoM encompasses both steps into one single integer mixed linear programming model, considering cranes and trucks schedule, fleet reduction, reduction of overtime, reduction of half-load transportation, and approaching the minimum distance traveled along a fixed planning horizon. Some technique constraints were implemented to provide accurate model function. An executed real problem data was used to compare the outcomes. The objective was to carry and transport 21,881.82 tons of lumber from 10 stands using a total of 48 trucks and 5 cranes in a planning horizon of 6 days, which each day has 20 hours of effective work. The FRoM has performed a fleet reduction of 72.92%, eliminating overtime. It has reduced the half-load trips to the order of 3.17% of all routes. The crane's analysis allowed catching points of inefficiency due to operational idleness. The FRoM provided savings of 49.12% at all logistic costs. FRoM has shown to be a good option as a route optimizer for forestry logistics.

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For viscously unstable, miscible Hele-Shaw displacements, we investigate the origin of the streamwise vorticity shown to be responsible for the inner splitting mechanism by Oliveira and Meiburg [J. Fluid Mech. 687 431 (2011)JFLSA70022-112010.1017/jfm.2011.367]. Towards this end, we compare 3D Navier-Stokes simulation results for neutrally buoyant, viscously unstable displacements and gravitationally unstable, constant viscosity ones. Only the former exhibit the generation of streamwise vorticity. The simulation results show that it is caused by the lateral displacement of the more viscous fluid by the less viscous one, with the variable viscosity terms playing a dominant role.

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One of the most important diseases of coffee plants is the coffee leaf rust fungus Hemileia vastatrix Berkeley and Broome (Uredinales). It can cause 30 % yield loss in some varieties of Coffea arabica (L.). Besides fungus, the coffee plants are attacked by phytophagous mites. The most common species is the coffee red mite, Oligonychus ilicis McGregor (Acari: Tetranychidae). Predatory mites of the Phytoseiidae family are well-known for their potential to control herbivorous mites and insects, but they can also develop and reproduce on various other food sources, such as plant pathogenic fungi. In a field survey, we found Ricoseius loxocheles (De Leon) (Acari: Phytoseiidae) on the necrotic areas caused by the coffee leaf rust fungus during the reproductive phase of the pathogen. We therefore assessed the development, survivorship and reproduction of R. loxocheles feeding on coffee leaf rust fungus and measured predation and oviposition of this phytoseiid having coffee red mite as prey under laboratory conditions. The mite fed, survived, developed and reproduced successfully on this pathogen but it was not able to prey on O. ilicis. Survival and oviposition with only prey were the same as without food. This phytoseiid mite does not really use O. ilicis as food. It is suggested that R. loxocheles is one phytoseiid that uses fungi as a main food source.

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BACKGROUND: An acaricidal effect of lime sulfur has not been demonstrated for Polyphagotarsonemus latus. However, lime sulfur can cause toxicity to natural enemies and to host plants. In this study, the toxicity of different concentrations of lime sulfur to P. latus, to the predatory mite Amblyseius herbicolus and to the predatory insect Chrysoperla externa was evaluated. Additionally, the phytotoxicity of lime sulfur to two P. latus hosts, chili pepper and physic nut plants, was determined. RESULTS: Lime sulfur at a concentration of 9.5 mL L(-1) restrained P. latus population growth. However, this concentration was deleterious to natural enemies. The predatory mite A. herbicolus showed a negative value of instantaneous growth rate, and only 50% of the tested larvae of C. externa reached adulthood when exposed to 10 mL L(-1) . Physic nut had severe injury symptoms when sprayed with all tested lime sulfur concentrations. For chili pepper plants, no phytoxicity was observed at any tested concentration. CONCLUSION: Lime sulfur might be used for P. latus control on chili pepper but not on physic nut owing to phytotoxicity. Care should be taken when using lime sulfur in view of negative effects on natural enemies. Selective lime sulfur concentration integrated with other management tactics may provide an effective and sustainable P. latus control on chili pepper.

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Tetranychus evansi Baker & Pritchard is an important pest of solanaceous plants, including tomatoes. This mite is characterized by a high reproductive rate, which leads to high population growth in a short period of time causing important economic damage. Control of T. evansi is mainly through synthetic acaricides. In searching for environmentally friendly control measures, we evaluated the efficiency of alternative products to control T. evansi on tomato plants under greenhouse conditions. The products tested were lime sulphur and neem based products. We first estimated the lethal concentration (LC) and instantaneous rate of increase (r i) of T. evansi exposed to different product concentrations in laboratory conditions, and later tested the efficacy of LC95 and the concentrations that restrained mite population growth (r i = 0) in greenhouse conditions. The following treatments were repeated three times: NeemPro (81.0 and 71.6 mg a.i./l), Natuneem (31.1 and 20.4 mg ai/l), Organic Neem (39.1 and 30.4 mg a.i./l), lime sulphur (1.0 and 0.6%) and water (control). For all products, control provided by LC95 was higher than provided for lower concentrations (r i = 0) one day after spraying. However, after five days, for both concentrations, the percentage of T. evansi population reduction was superior to 95% and increased over time. Only plants sprayed with Natuneem (31.1 mg a.i./l) showed symptoms of phytotoxicity. Lime sulphur and neem based products, applied in appropriate concentrations and formulations, bear out as a viable alternative to control T. evansi on tomato plants.

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Tetranychus evansi Baker & Pritchard is an important pest of solanaceous plants, including tomatoes. This mite is characterized by a high reproductive rate, which leads to high population growth in a short period of time causing important economic damage. Control of T. evansi is mainly through synthetic acaricides. In searching for environmentally friendly control measures, we evaluated the efficiency of alternative products to control T. evansi on tomato plants under greenhouse conditions. The products tested were lime sulphur and neem based products. We first estimated the lethal concentration (LC) and instantaneous rate of increase (r i) of T. evansi exposed to different product concentrations in laboratory conditions, and later tested the efficacy of LC95 and the concentrations that restrained mite population growth (r i = 0) in greenhouse conditions. The following treatments were repeated three times: NeemPro (81.0 and 71.6 mg a.i./l), Natuneem (31.1 and 20.4 mg ai/l), Organic Neem (39.1 and 30.4 mg a.i./l), lime sulphur (1.0 and 0.6 percent) and water (control). For all products, control provided by LC95 was higher than provided for lower concentrations (r i = 0) one day after spraying. However, after five days, for both concentrations, the percentage of T. evansi population reduction was superior to 95 percent and increased over time. Only plants sprayed with Natuneem (31.1 mg a.i./l) showed symptoms of phytotoxicity. Lime sulphur and neem based products, applied in appropriate concentrations and formulations, bear out as a viable alternative to control T. evansi on tomato plants.

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We study the behavior of a magnetorheological fluid droplet confined to a Hele-Shaw cell in the presence of an applied radial magnetic field. Interfacial pattern formation is investigated by considering the competition among capillary, viscoelastic, and magnetic forces. The contribution of a magnetic field-dependent yield stress is taken into account. Linear stability analysis reveals the stabilizing role played by yield stress. On the other hand, a mode-coupling approach predicts that the resulting fingering structures should become less and less sharp as yield stress effects are increased. By employing a vortex-sheet formalism we have been able to identify a family of exact stationary solutions of the problem, unveiling the development of swollen polygonal patterns. A suggestive magnetically controlled shape transition in which the edges of the patterns change from convex to concave has been also identified.

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We study the family of steady shapes which arise when a magnetic liquid droplet is confined in a rotating Hele-Shaw cell and subjected to an azimuthal magnetic field. Two different scenarios are considered: first, the magnetic fluid is assumed to be a Newtonian ferrofluid, and then it is taken as a viscoelastic magnetorheological fluid. The influence of the distinct material properties of the fluids on the ultimate morphology of the emerging stationary patterns is investigated by using a vortex-sheet formalism. Some of these exact steady structures are similar to the advanced time patterns obtained by existing time-evolving numerical simulations of the problem. A weakly nonlinear approach is employed to examine this fact and to gain analytical insight about relevant aspects related to the stability of such exact stationary solutions.

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The response of a ferrofluid droplet to a radial magnetic field is investigated, when the droplet is confined in a Hele-Shaw cell. We study how the stability properties of the interface and the shape of the emerging patterns react to the action of the magnetic field. At early linear stages, it is found that the radial field is destabilizing and determines the growth of fingering structures at the interface. In the weakly nonlinear regime, we have verified that the magnetic field favors the formation of peaked patterned structures that tend to become sharper and sharper as the magnitude of the magnetic effects is increased. A more detailed account of the pattern morphology is provided by the determination of nontrivial exact stationary solutions for the problem with finite surface tension. These solutions are obtained analytically and reveal the development of interesting polygon-shaped and starfishlike patterns. For sufficiently large applied fields or magnetic susceptibilities, pinch-off phenomena are detected, tending to occur near the fingertips. We have found that the morphological features obtained from the exact solutions are consistent with our linear and weakly nonlinear predictions. By contrasting the exact solutions for ferrofluids under radial field with those obtained for rotating Hele-Shaw flows with ordinary nonmagnetic fluids, we deduce that they coincide in the limit of very small susceptibilities.

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INTRODUCTION: The Brazilian variant of human immunodeficiency virus (HIV) type 1 (HIV-1) subtype B (serotype B'-GWGR) has a tryptophan replacing a proline in position 328 of the HIV-1 envelope, a feature that may induce a different HIV disease progression. We aimed to evaluate the role of the B subtypes of HIV-1 (serotypes B-GPGR and B'-GWGR) on HIV disease progression. METHODS: A total of 137 HIV-infected individuals who had been admitted to the hospital were tested with an anti-V3 serologic assay, using peptides representing 2 HIV-1 subtype B strains, MN and SF2, and 2 Brazilian variant B'-GWGR strains, BR1 and BR2. RESULTS: Of 137 serum samples tested with the anti-V3 serologic assay, 4 (3%) yielded indeterminate results, 74 (54%; from 25 women and 49 men) were found to be B-GPGR, and 59 (43%; from 20 women and 39 men) were found to be the B'-GWGR variant. In general, a longer interval from the first known positive HIV test result to an AIDS-defining event was observed in the B'-GWGR group than in the B-GPGR group (21 vs. 7 months). The CD4+ T cell counts were higher in the B'-GWGR group (median CD4+ T cell count, 65 vs. 31 cells/mm3; P=.01), and women infected with the B'-GWGR variant were less likely to die than were men infected with the same variant (P=.01). The median viral load in the B'-GWGR group was 3.395 copies/mL, compared with 39.350 copies/mL in the B-GPGR group (P=.01). CONCLUSIONS: Taken together, our results indicate that B'-GWGR-infected women may have more-favorable outcomes than B-GPGR-infected subjects.

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An analytical investigation is presented for the stretch flow of a viscous Newtonian ferrofluid highly confined between parallel plates. We focus on the development of interfacial instabilities when the upper plate is lifted at a described rate, under the action of an applied magnetic field. We derive the mode-coupling differential equation for the interface perturbation amplitudes and study both linear and nonlinear flow regimes. In contrast to the great majority of works in stretch flow we take into account stresses originated from velocity gradients normal to the ferrofluid interface. The impact of such normal stresses is accounted for through a modified Young-Laplace pressure jump interfacial boundary condition, which also includes the contribution from magnetic normal traction. We study how the stability properties of the interface and the shape of the emerging patterns respond to the combined action of normal stresses and magnetic field, both in the presence and absence of surface tension. We show that the inclusion of normal viscous stresses introduces a pertinent dependence on the initial aspect ratio, indicating that the number of fingers formed would be overestimated if such stresses are not taken into account. At early linear stages it is found that such stresses regularize the system, acting as an effective interfacial tension. At weakly nonlinear stages we verified that normal stresses reduce finger competition, which can be completely suppressed with the assistance of an azimuthal magnetic field. We have also found that the magnetic normal traction introduces a purely nonlinear contribution to the problem, revealing the key role played by the magnetic susceptibility in the control of finger competition.

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One efficient way of determining the bond strength of adhesives is to measure the force or the work required to separate two surfaces bonded by a thin adhesive film. We consider the case in which the thin film is not a conventional adhesive material but a high viscosity ferrofluid confined between two narrowly spaced parallel flat plates subjected to an external magnetic field. Our theoretical results demonstrate that both the peak adhesive force and the separation energy are significantly influenced by the action and symmetry properties of the applied field. Specifically, we show that the adhesive strength of a ferrofluid is reduced if the applied magnetic field is perpendicular to the plates or if the applied field is in plane and exhibits azimuthal symmetry. Conversely, the adhesive strength can be either enhanced or reduced if the applied field is in plane and is directed radially outward. This establishes an interesting connection between adhesion and ferrohydrodynamic phenomena, allowing the control of important adhesive properties by magnetic means.

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We consider the flow of a ferrofluid droplet in a Hele-Shaw cell with a time-dependent gap width. When the surface tension and applied magnetic field are zero, interfacial instabilities develop and the droplet breaks. We execute a mode-coupling approach to the problem and focus on understanding how the development of singularities is affected by the action of an external field. Our analytical results indicate that the introduction of an azimuthal magnetic field profoundly modifies pattern formation, allowing the inhibition of interfacial singularities. We suggest the magnetic field can be used as a controllable parameter to discipline singular behavior.