Pebrine disease, caused by Nosema bombycis (Nb) infection in silkworms, is a severe and long-standing disease that threatens sericulture. As parasitic pathogens, a complex relationship exists between microsporidia and their hosts at the mitochondrial level. Previous studies have found that the translocator protein (TSPO) is involved in various biological functions, such as membrane potential regulation, mitochondrial autophagy, immune responses, calcium ion channel regulation, and cell apoptosis. In the present study, we found that TSPO expression in silkworms (BmTSPO) was upregulated following Nb infection, leading to an increase in cytoplasmic calcium, adenosine triphosphate, and reactive oxygen species levels. Knockdown and overexpression of BmTSPO resulted in the promotion and inhibition of Nb proliferation, respectively. We also demonstrated that the overexpression of BmTSPO promotes host cell apoptosis and significantly increases the expression of genes involved in the immune deficiency and Janus kinase-signal transducer and the activator of the transcription pathways. These findings suggest that BmTSPO activates the innate immune signalling pathway in silkworms to regulate Nb proliferation. Targeting TSPO represents a promising approach for the development of new treatments for microsporidian infections.

An efficient and accurate numerical scheme is proposed for solving the transverse electric (TE) mode electromagnetic (EM) propagation problem in two-dimensional earth. The scheme is based on the alternating direction finite-difference time-domain (ADI-FDTD) method. Unlike the conventional upward continuation approach for the earth-air interface, an integral formulation for the interface boundary is developed and it is effectively incorporated to the ADI solver. Stability and convergence analysis together with an error estimate are presented. Numerical simulations are carried out to validate the proposed method, and the advantage of the present method over the popular Du-Fort-Frankel scheme is clearly demonstrated. Examples of the electromagnetic field propagation in the ground with anomaly further verify the effectiveness of the proposed scheme.

We present an analytical theory of scattering of tide-generated internal gravity waves in a continuously stratified ocean with a randomly rough seabed. Based on a linearized approximation, the idealized case of constant mean sea depth and Brunt–Väisälä frequency is considered. The depth fluctuation is assumed to be a stationary random function of space, characterized by small amplitude and a correlation length comparable to the typical wavelength. For both one- and two-dimensional topographies the effects of scattering on the wave phase over long distances are derived explicitly by the method of multiple scales. For one-dimensional topography, numerical results are compared with Bühler & Holmes-Cerfon (J. Fluid Mech., vol. 678, 2011, pp. 271–293), computed by the method of characteristics. For two-dimensional topography, new results are presented for both statistically isotropic and anisotropic cases.

Motivated by potential applications for offshore airports supported on vertical piles, we report a theory of wave diffraction by a periodic array of circular cylinders. The simple case of normal incidence on a rectangular array is studied here, which is equivalent to a line array along the centre of a long channel. An asymptotic theory is developed for cylinders much smaller than the incident wavelength, which is comparable to the cylinder spacing. Focus is on Bragg resonance near which scattering is strong. A combination of the method of multiple scales and the Bloch theorem leads to simple evolution equations coupling the wave envelopes. Dispersion of transient wave envelopes is investigated. Scattering of detuned waves by a large but finite number of cylinders is investigated for frequencies in and outside the band gap. Quantitative accuracy is assessed by comparisons with numerical computations via finite elements. The analytical theory prepares the ground for nonlinear studies and may facilitate future inclusion of real-fluid effects such as vortex shedding.

It is known that perfectly trapped surface waves exist at certain eigenfrequencies near a vertical cylinder in a long channel, or an infinite and periodic array of vertical cylinders, and excitation by incident waves of the same frequency is not possible according to the linear theory. We present a nonlinear theory whereby a trapped wave near a cylinder in a channel is excited subharmonically by an incident wave of twice the eigenfrequency. The effects of geometrical parameters on the initial growth of resonance and the final amplification are studied in detail.

The nonlinear long waves generated by a disturbance moving at subcritical, critical and supercritical speed in unbounded shallow water are investigated. The problem is formulated by a new modified generalized Boussinesq equation and solved numerically by an implicit finite-difference algorithm. Three-dimensional upstream solitary waves with significant amplitude are generated with a periodicity by a pressure distribution or slender strut advancing on the free surface. The crestlines of these solitons are almost perfect parabolas with decreasing curvature with respect to time. Behind the disturbance, a complicated, divergent Kelvin-like wave pattern is formed. It is found that, unlike the wave breaking phenomena in a narrow channel at Fh [ges ] 1.2, the three- dimensional upstream solitons form several parabolic water humps and are blocked ahead of the disturbance at supercritical speed in an unbounded domain for large time.