This study investigates the quasi-static indentation response of end-grain balsa wood sandwich composites with glass, basalt, glass-carbon, and basalt-carbon FRP facesheets. The effects of facesheet configuration, indenter diameter, and loading rate were evaluated using 17 and 20 mm spherical indenters at 1.25 and 2.5 mm/min. ANOVA results showed that facesheet configuration and indenter diameter significantly affected the response, while loading rate showed no significant main effect, although significant interactions were found for the maximum contact load. Replacing glass with basalt generally increased the maximum contact load and displacement at maximum load, while the absorbed energy up to the maximum contact load increased by up to 48.26% in the non-carbon configuration. Carbon hybridization increased the maximum contact load by up to 33.13% and the absorbed energy by up to 78.47%, while reducing the initial indentation rigidity. The main failure modes were matrix cracking, fiber breakage, facesheet delamination, balsa core crushing, and core/facesheet debonding. The results show that basalt fibers are a promising alternative to glass fibers for improving load-bearing capacity and energy absorption under localized indentation, while carbon hybridization further improves maximum load and deformation capacity.
Two-dimensional shear wave elastography (2D-SWE) provides quantitative information on tissue stiffness over a broad field of view, but physiological values for feline testes remain poorly defined. This study aimed to characterize testicular stiffness in clinically healthy cats and to compare different regions of interest (ROIs), and explore agreement between focal and extended sampling strategies. Nineteen client-owned intact male cats presented for elective bilateral orchiectomy were included after clinical, ultrasonographic, and histopathological screening. Before surgery, both testes underwent B-mode, Doppler, and 2D-SWE examination using a Mindray DC-80A ultrasound system with a linear transducer. In longitudinal scans, two circular ROIs were placed above and two below the testicular mediastinum, and an additional ROI encompassed the whole testis. Mean shear wave speed (SWS) values were calculated for each sampling strategy. Histopathology confirmed normal testicular tissue in all cases. Mean SWS was 2.45 f 0.62 m/s in the right testis and 2.73 f 0.51 m/s in the left, with no significant difference between sides (p = 0.097). Mean values were 2.51 f 0.55 m/s in submediastinal regions and 2.66 f 0.42 m/s in supramediastinal regions, without significant differences (p = 0.129). Whole-testis, submediastinal, and supramediastinal ROIs yielded mean SWS values of 2.62, 2.51, and 2.66 m/s, respectively, with no significant differences among approaches (p = 0.080). Exploratory agreement analyses showed small mean biases between the extended and focal ROI approaches, but did not establish interchangeability. These findings support the feasibility of 2D-SWE for assessing feline testicular stiffness and suggest a relatively homogeneous stiffness distribution in healthy feline testes. Further studies are needed to assess repeatability, establish reference intervals, and investigate diagnostic performance for feline testicular disease in clinical practice.
This work investigates how toxin-mediated interactions and directed movements shape the emergence of coherent structures in plant-herbivore systems. The analysis focuses on a two-compartment model enclosing a toxin-dependent functional response and a cross-diffusion term that represents ecologically plausible herbivores' movement towards, or away from, vegetation. Two distinct dynamical regimes arise depending on toxicity strength. Under weak toxicity, the system admits at most one biologically feasible coexistence equilibrium, which may lose stability through a Hopf bifurcation generating small-amplitude temporal oscillations. Under strong toxicity, the nonlinear functional response becomes non-monotonic, allowing for multiple coexistence equilibria and abrupt regime shifts. The influence of cross-diffusion on stability is also examined, identifying the conditions under which Turing instabilities and mixed spatiotemporal patterns occur. Near the corresponding bifurcation thresholds, Stuart-Landau amplitude equations are derived via weakly nonlinear analysis, providing a unified framework for the modulation of oscillatory, stationary, and combined Turing-Hopf modes. Numerical simulations corroborate the theoretical predictions, illustrating transitions from spatially uniform states to oscillations, spatial patterns, and mixed behavior. Overall, this manuscript highlights how chemical defences, nonlinear feedbacks, and movement strategies jointly determine the emergence, selection, and robustness of coherent structures in plant-herbivore systems.
This study examines whether investments in digital technologies raise export sales among low-tech firms, and whether cybersecurity spending conditions these returns. Reading the Resource-Based View through resource orchestration, we frame digital technologies as enabling resources and cybersecurity as a protective commitment securing their value but competing for the investment budget under scarcity. This competition is sharper in lowtech firms, with thinner slack. Using Bank of Italy data (2016-2023), we find digital investment positively associated with export sales where cybersecurity spending is absent. This association is negative in the highest protective-spending brackets, and a specification imposing no functional form locates the reversal at the top of the distribution. The pattern is clearer among SMEs and manufacturing firms; among larger firms, digital investment shows no association with exports, while protective spending is associated with higher export volume. This is a cyber-risk paradox: under scarcity, protection substitutes for, rather than complements, digital expansion.
