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Ubiquitous, industrial use of bottom‐towed fishing gear since the 1800s has altered marine communities and ecosystem services. Outside of legal protection, only areas inaccessible to trawlers are offered any protection. Shipwrecks present hazards to fishing gear and are rarely subject to trawling pressure. As many have been in situ for >100 years, they offer a baseline of ecological potential when trawling pressure is reduced or removed. Five shipwrecks were surveyed off the Berwickshire coast, some within the Static Gear Reserve and others outside. Video transects were collected of shipwrecks, the surrounding 50 m radius and control locations >150 m from the wreck site. Species identified were assigned a category based on their vulnerability to trawling. The effect of distance from a shipwreck on ecological communities within sites Open and Closed to trawling was investigated. The ecological importance of shipwrecks increased relative to trawling pressure. In Open sites, abundance was 340% greater on Wreck locations than Control. Conversely, within Closed sites, abundance was 149% greater in Control locations than Wreck. In Open sites, shipwreck communities are more similar to those in Closed sites, than to the habitat surrounding the shipwreck. Vulnerable species, mostly large, sessile filter feeders, are almost entirely absent from Open sites, but account for ~28% of the total abundance on shipwrecks in Closed sites. This study offers a quantifiable method to evaluate the ecological contribution of shipwrecks in disturbed areas and suggests their role may warrant further research, and consideration in conservation policy, such as inclusion in 30 × 30 objectives. Our findings also demonstrate the possible ecological gains of expanding or including static gear reserves across Marine Protected Areas. [ABSTRACT FROM AUTHOR]

C. pagurus and H. gammarus are deemed to be declining in abundance in the Berwickshire Marine Reserve from personal communications with local inshore fishers. Fisheries data in the form of catch per unit effort (CPUE) were collected for these two commercially important decapods. Other explanatory variables from fishing activity such as the creel and bait type used, the soak time of the fishing gear, and deployment depth were recorded to provide as much detail as possible to describe the effort applied to catch these decapod species. In this study, CPUE was higher for H. gammarus and C. pagurus outside the Berwickshire Marine Reserve. General additive models (GAMs) were used to describe the effects of the explanatory variables and showed that soak time (days) and depth (m) significantly affected CPUE for C. pagurus, not H. gammarus. Sea temperature (°C) showed a negative correlation with the CPUE of both H. gammarus and C. pagurus; however, a positive correlation was found with the number of C. pagurus caught. The data collected in this study provide a foundation in understanding the current abundance of C. pagurus and H. gammarus in a voluntary marine reserve on the east coast of Scotland, which can be used to inform future changes in fisheries management in Berwickshire. [ABSTRACT FROM AUTHOR]

The literature suggests regional variations in the size at which sexual maturity is reached for commercially important edible crab (Cancer pagurus), worth GBP 74.3 million annually, which could have implications for regional fisheries management. Berwickshire and Northumberland are geographically divided by the Scotland and England border and remain within the Berwickshire and North Northumberland Coast SAC (Special Area of Conservation). Each are managed by differing fisheries authorities and Minimum Conservation Reference Sizes (MCRS). Morphometric measurements were recorded for each C. pagurus individual to categorise morphometric maturity using segmented regression, with gonadal maturity categorised using visual gonad characteristics and general linear model regressions to compare onset in sexual maturity. Results showed regional variations for gonadal maturity with males reaching sexual onset at a carapace width size of 108.5 mm in Berwickshire and 109.9 mm in Northumberland; females at a size of 126.8 mm in Berwickshire and 120.8 mm in Northumberland. This was also true for morphometric maturity based on chelae height, that males (141.1 mm) and females (134.7 mm) from Berwickshire were morphometrically mature at greater sizes than males (130.1 mm) and females (120.8 mm) from Northumberland. This study shows that the respective MCRS in both regions are appropriate for the C. pagurus populations, but implications for fisheries management could be present. [ABSTRACT FROM AUTHOR]

This article presents the design and analysis of a staggered double-vane (SDV) slow-wave structure (SWS) for $W$ -band amplifier, with 20-dB gain and a very high bandwidth (~25%). The use of dual Bragg reflector at either end of the interaction structure increases the impedance matching and the radio frequency (RF) coupling efficiency at the input and output ports, thereby reducing the RF leakage at the electron gun and collector ends, from 15% to 25% to less than 0.6%. The attenuator section is simple to fabricate and optimally designed in order to provide an effective isolation (>20 dB) between the input RF signal in the input section and the RF signal reflected from the output section. The dispersion analysis, the transmission analysis of each section, and the beam–wave interactions were simulated using the Dassault system’s computer simulation technology (CST) eigenmode solver, time-domain solver, and the particle-in-cell (PIC) solver, respectively. The proposed design of the SDV SWS conclusively provides an enormous bandwidth of ~25 GHz with 20-dB gain for $W$ -band amplifier, when compared to its solid-state counterparts and earlier reported work as per the author’s knowledge. [ABSTRACT FROM AUTHOR]

The large-signal behavior of traveling wave tube amplifier for a linear beam dielectric loaded anisotropically conducting tape helix slow wave structure (SWS) is realized through a swift and reliable field analysis. Using Green’s function sequence, the field components in the SWS are designated as nonlinear functionals of electron arrival time. The electron arrival time in the beam region is formulated into a nonlinear operator in the Banach space mapping form by substituting the axial electric field component into the electron ballistic equation. The nonlinear beam–wave interaction is then obtained by determining the electron arrival time through extensive successive approximations, and thus exact electric and magnetic field components in the tape helix SWS are attained. The numerical computation of the proposed model yields definitive analytical results for the electron exit velocity, induced surface current density, power gain, conversion efficiency, and optimum interaction length. [ABSTRACT FROM PUBLISHER]

The homogeneous boundary value problem existing in the electromagnetic wave propagation in a dielectricloaded perfectly conducting tape helix with infinitesimal tape thickness is investigated in this study. The ill-posed boundary value problem is regularised using the mollification method. The homogeneous boundary value problem is solved for the dielectric loaded perfectly conducting tape helix taking into account the exact boundary conditions for the perfectly conducting dielectric loaded tape helix. The solved approximate dispersion equation takes the form of the solvability condition for an infinite system of linear homogeneous equations namely, the determinant of the infinite order coefficient matrix is zero. For the numerical computation of the dispersion equation, all the entries of the symmetrically truncated version of the coefficient matrix are estimated by summing an adequate number of the rapidly converging series for them. The tape-current distribution is estimated from the null-space vector of the truncated coefficient matrix corresponding to a specified root of the dispersion equation. The numerical results suggest that the propagation characteristic computed by the anisotropically conducting model (that neglects the component of the tape-current density perpendicular to the winding direction) is only an abstinent approximation to consider for moderately wide tapes. [ABSTRACT FROM AUTHOR]

A personal narrative is presented which explores the author's experience of being a student of theater in the Dartington College of Arts from 1966 to 1968.