On the hydrodynamics and heat convection of an impinging external flow upon a cylinder with transpiration and embedded in a porous medium

This paper extends the existing studies of heat convection by an external flow impinging upon a flat porous insert to that on a circular cylinder inside a porous medium. The surface of the cylinder is subject to constant temperature and can include uniform or non-uniform transpiration. These cylindrical configurations are introduced in the analyses of stagnation point flows in porous media for the first time. The equations governing steady transport of momentum and thermal energy in porous media are reduced to simpler nonlinear differential equations and subsequently solved numerically. This reveals the dimensionless velocity and temperature fields of the stagnation-point flow, as well as the Nusselt number and shear stress on the surface of the cylinder. The results show that transpiration on the surface of the cylinder and Reynolds number of the external flow dominate the fluid dynamics and heat transfer problems. In particular, non-uniform transpiration is shown to significantly affect the thermal and hydrodynamic responses of the system in the circumferential direction. However, the permeability and porosity of the porous medium are found to have relatively smaller influences

Cross-tolerance to biotic and abiotic stresses in plants: a focus on resistance to aphid infestation

Plants co-evolved with an enormous variety of microbial pathogens and insect herbivores under daily and seasonal variations in abiotic environmental conditions. Hence, plant cells display a high capacity to respond to diverse stresses through a flexible and finely balanced response network that involves components such as reduction-oxidation (redox) signalling pathways, stress hormones and growth regulators, as well as calcium and protein kinase cascades. Biotic and abiotic stress responses use common signals, pathways and triggers leading to cross tolerance phenomena, whereby exposure to one type of stress can activate plant responses that facilitate tolerance to several different types of stress. While the acclimation mechanisms and adaptive responses that facilitate responses to single biotic and abiotic stresses have been extensively characterised, relatively little information is available on the dynamic aspects of combined biotic/abiotic stress response. In this review, we consider how the abiotic environment influences plant responses to attack by phloem-feeding aphids. Unravelling the signalling cascades that underpin cross tolerance to biotic and abiotic stresses will allow the identification of new targets for increasing environmental resilience in crops

Affinity of Tau antibodies for solubilized pathological Tau species but not their immunogen or insoluble Tau aggregates predicts in vivo and ex vivo efficacy

BACKGROUND: A few tau immunotherapies are now in clinical trials with several more likely to be initiated in the near future. A priori, it can be anticipated that an antibody which broadly recognizes various pathological tau aggregates with high affinity would have the ideal therapeutic properties. Tau antibodies 4E6 and 6B2, raised against the same epitope region but of varying specificity and affinity, were tested for acutely improving cognition and reducing tau pathology in transgenic tauopathy mice and neuronal cultures. RESULTS: Surprisingly, we here show that one antibody, 4E6, which has low affinity for most forms of tau acutely improved cognition and reduced soluble phospho-tau, whereas another antibody, 6B2, which has high affinity for various tau species was ineffective. Concurrently, we confirmed and clarified these efficacy differences in an ex vivo model of tauopathy. Alzheimer’s paired helical filaments (PHF) were toxic to the neurons and increased tau levels in remaining neurons. Both toxicity and tau seeding were prevented by 4E6 but not by 6B2. Furthermore, 4E6 reduced PHF spreading between neurons. Interestingly, 4E6’s efficacy relates to its high affinity binding to solubilized PHF, whereas the ineffective 6B2 binds mainly to aggregated PHF. Blocking 4E6's uptake into neurons prevented its protective effects if the antibody was administered after PHF had been internalized. When 4E6 and PHF were administered at the same time, the antibody was protective extracellularly. CONCLUSIONS: Overall, these findings indicate that high antibody affinity for solubilized PHF predicts efficacy, and that acute antibody-mediated improvement in cognition relates to clearance of soluble phospho-tau. Importantly, both intra- and extracellular clearance pathways are in play. Together, these results have major implications for understanding the pathogenesis of tauopathies and for development of immunotherapies. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13024-016-0126-z) contains supplementary material, which is available to authorized users

A Global Model of Technological Utilization Based on Governmental, Business Investment, Social, and Economic Factors

This paper presents a model of governmental support and openness, business and technology investment, and socio-economic factors that influence technological utilization for 110 countries. The conceptual framework is based on prior research showing that these factors impact the usage of technology and vice versa. Structural equation modeling is applied to conceptualize and test the model. This model uses latent and observable variables and the application tests five hypotheses for the overall model and relationships between its factors. Data are recent and from the World Bank and World Economic Forum. The findings indicate a critical pathway of influences between the factors of government support and openness, socio-economic level, and technology utilization. The paper suggests policy steps for national governments of developed and developing nations especially for policy clusters of government emphasis on ICT, openness, and strengthening of R&D and technology investment

Exposure to violence and beliefs about violence against women among adolescents in Nigeria and South Africa

Abstract: Although adolescents’ exposure to violence and oppressive gender attitudes is prevalent, comparative knowledge across countries is sparse. This study examined exposure to intimate partner violence (IPV), family violence, and beliefs about violence against women (VAW) in a convenience sample of 2,462 adolescents from 44 schools in Nigeria and South Africa. Findings suggested that exposure to IPV, family violence, and beliefs about VAW differed by gender and country. Specifically, adolescents from Nigeria were more likely to be exposed to IPV and family violence and were more likely to endorse VAW than adolescents from South Africa. Male adolescents were more likely to endorse VAW than were female adolescents. Similarly, higher age, being male, being from Nigeria, being in a relationship, and greater exposure to family violence were associated with higher endorsement of VAW. Findings suggest that effective prevention programs are needed in both countries to mitigate exposure to IPV and family violence. Concerted efforts are also required to work with exposed adolescents to inhibit pro-VAW beliefs and stop the intergenerational transmission of violence. Additional implications of findings for policy, practice, and research are discussed

Transient analysis of the interactions between a heat transferring, radial stagnation flow and a rotating cylinder-magnetohydrodynamic and non-uniform transpiration effects

This paper aims at providing further understanding on the fluid flow and heat transfer processes in unsteady rotating systems with mass transpiration. Such systems can be found in chemical separators, hydraulic systems, and printing devices. To this end, an unsteady viscous flow in the vicinity of an unaxisymmetric stagnation-point on a rotating cylinder is examined. The nonuniform transpiration and a transverse magnetic field are further considered. The angular speed of the cylinder and the thermal boundary conditions are expressed by time-dependent functions. A reduction of the Navier–Stokes and energy equations is obtained through using appropriate similarity transformations. The semisimilar solution of the Navier–Stokes equations and energy equation are developed numerically using an implicit finite difference scheme. Pertinent parameters including the Reynolds number and magnetic parameter and transpiration function are subsequently varied systematically. It is shown that the transpiration function can significantly affect the thermal and hydrodynamic behaviors of the system. In keeping with the findings in other areas of magnetohydrodynamics (MHD), the results show that the applied magnetic field has modest effects on the Nusselt number. However, it is demonstrated that the magnetic effects can significantly increase the imposed shear stress on the surface of the rotating cylinder

Coevolved mutations reveal distinct architectures for two core proteins in the bacterial flagellar motor

Switching of bacterial flagellar rotation is caused by large domain movements of the FliG protein triggered by binding of the signal protein CheY to FliM. FliG and FliM form adjacent multi-subunit arrays within the basal body C-ring. The movements alter the interaction of the FliG C-terminal (FliGC) "torque" helix with the stator complexes. Atomic models based on the Salmonella entrovar C-ring electron microscopy reconstruction have implications for switching, but lack consensus on the relative locations of the FliG armadillo (ARM) domains (amino-terminal (FliGN), middle (FliGM) and FliGC) as well as changes during chemotaxis. The generality of the Salmonella model is challenged by the variation in motor morphology and response between species. We studied coevolved residue mutations to determine the unifying elements of switch architecture. Residue interactions, measured by their coevolution, were formalized as a network, guided by structural data. Our measurements reveal a common design with dedicated switch and motor modules. The FliM middle domain (FliMM) has extensive connectivity most simply explained by conserved intra and inter-subunit contacts. In contrast, FliG has patchy, complex architecture. Conserved structural motifs form interacting nodes in the coevolution network that wire FliMM to the FliGC C-terminal, four-helix motor module (C3-6). FliG C3-6 coevolution is organized around the torque helix, differently from other ARM domains. The nodes form separated, surface-proximal patches that are targeted by deleterious mutations as in other allosteric systems. The dominant node is formed by the EHPQ motif at the FliMMFliGM contact interface and adjacent helix residues at a central location within FliGM. The node interacts with nodes in the N-terminal FliGc α-helix triad (ARM-C) and FliGN. ARM-C, separated from C3-6 by the MFVF motif, has poor intra-network connectivity consistent with its variable orientation revealed by structural data. ARM-C could be the convertor element that provides mechanistic and species diversity.JK was supported by Medical Research Council grant U117581331. SK was supported by seed funds from Lahore University of Managment Sciences (LUMS) and the Molecular Biology Consortium

Effect of vitamin C on N,N′-dimethyl-4,4′-bipyridinium dichloride-induced hepatic and renal toxicity in Swiss albino mice

Purpose: To evaluate the effectiveness of vitamin C on paraquat-induced hepatic and renal toxicity in Swiss albino mice.Methods: Three groups of Swiss albino mice (n = 10), i.e., control, paraquat (15 mg/kg) and paraquat (15 mg/kg) + vitamin C (20 mg/kg) were used in the study. The drugs were administered intraperitoneally for four days. Blood samples were collected on day 5 for determination of serum levels of liver and renal biomarkers. Thereafter, the animals were sacrificed; liver and kidney were excised and preserved in neutral formalin for histopathological analysis.Results: The paraquat-treated animals showed higher levels of aspartate transaminase (AST), alanine transaminase (ALT), serum urea and creatinine, relative to values for control. Histopathological examination of the paraquat-treated animals showed cytoplasmic vacuolar degeneration and congestion of central vein in the liver, and glomerular necrosis in the kidneys. Control and vitamin C-treated mice showed normal architecture of liver and kidney.Conclusion: These results indicate that vitamin C modulated the paraquat-induced liver and renal abnormalities in the experimental animals. Thus vitamin C exerts hepatoprotective and renoprotective effects against paraquat poisoning.Keywords: Paraquat poisoning, Liver, Kidney, Vitamin C, Toxicity, Histopatholog

Cross-talk between high light stress and plant defence to the two-spotted spider mite in Arabidopsis thaliana

Little is known about how plants deal with arthropod herbivores under the fluctuating light intensity and spectra which occur in natural environments. Moreover, the role of simultaneous stress such as excess light (EL) in the regulation of plant responses to herbivores is poorly characterized. In the current study, we focused on a mite-herbivore, specifically, the two-spotted spider mite (TSSM), which is one of the major agricultural pests worldwide. Our results showed that TSSM-induced leaf damage (visualized by trypan blue staining) and oviposition rate (measured as daily female fecundity) decreased after EL pre-treatment in wild-type Arabidopsis plants, but the observed responses were not wavelength specific. Thus, we established that EL pre-treatment reduced Arabidopsis susceptibility to TSSM infestation. Due to the fact that a portion of EL energy is dissipated by plants as heat in the mechanism known as non-photochemical quenching (NPQ) of chlorophyll fluorescence, we tested an Arabidopsis npq4-1 mutant impaired in NPQ. We showed that npq4-1 plants are significantly less susceptible to TSSM feeding activity, and this result was not dependent on light pre-treatment. Therefore, our findings strongly support the role of light in plant defence against TSSM, pointing to a key role for a photo-protective mechanism such as NPQ in this regulation. We hypothesize that plants impaired in NPQ are constantly primed to mite attack, as this seems to be a universal evolutionarily conserved mechanism for herbivores