We utilize resolvent and weakly nonlinear analyses in combination with direct numerical simulations (DNS) to identify mechanisms for oblique transition in a Mach $5$ hypersonic flow over an adiabatic slender double wedge. Even though the laminar separated flow is globally stable, resolvent analysis demonstrates significant amplification of unsteady external disturbances to the linearized flow equations. These disturbances are introduced upstream of the separation zone and they lead to the appearance of oblique waves further downstream. We demonstrate that the large amplification of oblique waves arises from the growth of fluctuation shear stress due to streamline curvature of the laminar base flow in the separated shear layer. This is in contrast to the attached boundary layers, where no such mechanism exists. We also use a weakly nonlinear analysis to show that the resolvent operator associated with linearization around the laminar base flow governs the evolution of steady reattachment streaks that arise from quadratic interactions of unsteady oblique waves. These quadratic interactions generate vortical excitations in the reattaching shear layer which lead to the formation of streaks in the recirculation zone and their subsequent amplification, breakdown and transition to turbulence downstream. Our analysis of the energy budget shows that deceleration of the base flow near reattachment is primarily responsible for amplification of steady streaks. Finally, we employ DNS to examine latter stages of transition to turbulence and demonstrate the predictive power of a weakly nonlinear input–output framework in uncovering triggering mechanisms for oblique transition in separated high-speed boundary layer flows.

When a fluid stream in a conduit splits in order to pass around an obstruction, it is possible that one branch will be critically controlled while the other remains not so. This is apparently the situation in Pacific Ocean abyssal circulation, where most of the northward flow of Antarctic bottom water passes through the Samoan Passage, where it is hydraulically controlled, while the remainder is diverted around the Manihiki Plateau and is not controlled. These observations raise a number of questions concerning the dynamics necessary to support such a regime in the steady state, the nature of upstream influence and the usefulness of rotating hydraulic theory to predict the partitioning of volume transport between the two paths, which assumes the controlled branch is inviscid. Through the use of a theory for constant potential vorticity flow and accompanying numerical model, we show that a steady-state regime similar to what is observed is dynamically possible provided that sufficient bottom friction is present in the uncontrolled branch. In this case, the upstream influence that typically exists for rotating channel flow is transformed into influence into how the flow is partitioned. As a result, the partitioning of volume flux can still be reasonably well predicted with an inviscid theory that exploits the lack of upstream influence.

In the present study, the nematicidal activity of a Moringa oleifera ethyl acetate leaf extract against the eggs and larvae of Haemonchus contortus and Nacobbus aberrans, nematodes of agricultural importance, was evaluated. The experimental design for the evaluation of the effects against both nematodes consisted of eight treatments (n = 4). Distilled water, Tween (4%) and a commercial anthelmintic agent (ivermectin, 5 mg/mL) were used as controls, and for treatments 4–8, the concentrations of the extract were 20, 10, 5, 2.5 and 1.25 mg/mL, respectively. Readings were taken at 12 h and 24 h for N. aberrans and 48 h and 72 h for H. contortus post-treatment under an optical microscope (10× and 40×). The data obtained were analysed by analysis of variance through a completely randomized factorial design using the SAS V9 program. The results show that, for H. contortus egg hatching, 85.88% inhibition was obtained at a concentration of 20 mg/mL at 48 h, while for third-stage larva (L3) mortality, the highest percentage was 68.19% at 1.25 mg/mL at 72 h. In the case of N. aberrans, the greatest inhibition of egg hatching was 90.69% at 5 mg/mL at 12 h post-treatment, and for larval mortality, it was 100% at 10 mg/mL at 24 h post-treatment. The main major compounds identified by qualitative analysis and by gas chromatography coupled to mass spectrometry were 9,12,15-octadecatrienoic acid, (Z,Z,Z)-, n-hexadecanoic acid and 2,4-di-tert-butylphenol, and the minor compounds included phytol, γ-sitosterol and α-tocopheryl acetate. It was demonstrated that the ethyl acetate leaf extract of M. oleifera Lam. shows great potential for combating agricultural nematodes.

Firm operators continually manage multiple sources of risk. In an application to cattle feedlot operations, our objective is to determine if producers view output price and animal health risks separately or jointly. We conduct a survey with a choice experiment placing operators in forward looking, decision-making scenarios, and capture information on past risk management approaches. Evidence regarding a relationship between animal health and output price risk mitigation is mixed and depends on the decision being made. Combined, these results provide new insight into how managers approach multiple risks when facing resource constraints.

To establish flutter onset boundaries on the flight envelope, it is required to determine the flutter onset dynamic pressure. Proper selection of a flight flutter prediction technique is vital to flutter onset speed prediction. Several methods are available in literature, starting with those based on velocity damping, envelope functions, flutter margin, discrete-time Autoregressive Moving Average (ARMA) modelling, flutterometer and the Houbolt–Rainey algorithm. Each approach has its capabilities and limitations. To choose a robust and efficient flutter prediction technique from among the velocity damping, envelope function, Houbolt–Rainey, flutter margin and auto-regressive techniques, an example problem is chosen for their evaluation. Hence, in this paper, a three-degree-of-freedom model representing the aerodynamics, stiffness and inertia of a typical wing section is used(1). The aerodynamic, stiffness and inertia properties in the example problem are kept the same when each of the above techniques is used to predict the flutter speed of this aeroelastic system. This three-degree-of-freedom model is used to generate data at speeds before initiation of flutter, during flutter and after occurrence of flutter. Using these data, the above-mentioned flutter prediction methods are evaluated and the results are presented.

The main goal of this work was to evaluate the in vitro biological activity of two ferrocenyl chalcones (FcC-1 and FcC-2) against Haemonchus contortus (third-stage larvae (L3)) and Nacobbus aberrans (second-stage juveniles (J2)). Both compounds were synthesized and characterized by usual spectroscopic methods and their molecular structures were confirmed by single-crystal X-ray diffractometry. Nematode strains were examined in terms of percentage mortality of H. contortus (L3) by the action of FcC-1, which showed an effectivity of 100% at a concentration of 342 μM in 24 h, with EC50 = 20.33 μM and EC90 = 162.76 μM, whereas FcC-2 had an effectivity of 72% at a concentration of 342 μM in 24 h, with EC50 = 167.39 μM and EC90 = 316.21 μM. The effect of FcC-1 against nematode phytoparasite N. aberrans showed a better percentage of 95% at a concentration of 342 μM, with EC50 = 7.18 μM and EC90 = 79.25 μM, whereas the effect of FcC-2 was 87% at 342 μM, with EC50 = 168 μM and EC90 = 319.56 μM at 36 h. After treatment, the scanning electron micrographs revealed deformities in the dorsal flank and posterior part close to the tail of H. contortus L3. They showed moderate in vitro nematicidal activity against H. contortus L3 and N. aberrans J2.

It is known now that the dynamics and prognosis of stress-related disorders depends on the persistence of stress syndrome (re-experiencing, avoidance/overcoming, arousal) related to the symptoms of anxiety. Much less attention had paid to other ways of dynamics of stress-related disorders. The preliminary results of the investigation of stress-related disorders in general and specialized medical practice have shown three affective ways of psychic trauma fixation and stress-related disorders persistence – anxious, melancholic and apathetic. For further elaboration of affective model of stress-related disorders integrated psychiatric and psychological approach is applying.