This review considers factors affecting the flight capacity of carabid beetles and the implications of flight for carabids. Studies from the Dutch polders in particular show that young populations of carabids consist predominantly of macropterous species and macropterous individuals of wing-dimorphic species. Also populations of wing-dimorphic carabid species at the periphery of their geographical range contain high proportions of macropterous individuals. However, studies from Baltic archipelagos show that older populations of even highly isolated island habitats contain considerable proportions of brachypterous species and individuals. This suggests that macroptery is primarily an adaptation for dispersal and that there exists a mechanism for subsequently reducing the ratio of macropterous to brachypterous species under stable conditions, due to the competitive advantage of brachyptery. Populations in isolated habitats, such as islands and mountains, have high proportions of brachypterous species. Many macropterous species do not possess functional flight muscles. Species of unstable habitats, such as tree canopies and wet habitats, are mostly macropterous. Brachypterous species tend to disappear from disturbed habitats. There is uncertainty regarding the extent to which carabid dispersal is directed and how much passive. Both Den Boer and Lindroth recognized that mostly macropterous individuals of macropterous and wing-dimorphic species disperse and found new populations, after which brachyptery tends to rapidly appear and proliferate in the newly founded population. It is most likely that the allele for brachyptery would arrive via the dispersal of gravid females which had mated with brachypterous males prior to emigration. Whilst many studies consider wing morphology traits of carabid beetles to be species-specific and permanent, a number of studies have shown that the oogenesis flight syndrome, whereby females undertake migration and subsequently lose their flight muscles by histolysis before eventually regenerating them after reproducing, has been reported for a growing number of carabid species. Wing morphology of carabid beetles clearly offers strong potential for the study of population dynamics. This field of study flourished during the 1940's to the late 1980's. Whilst a considerable amount of valuable research has been performed and published, the topic clearly holds considerable potential for future study., Stephen Venn., and Obsahuje bibliografii
For low-alloyed cast ferritic steel simultaneous effect of temperature and notch root radius on fracture toughness has been investigated. Due to fact that fracture tests were performed on notched specimens (cylindrical tensile specimens with circumferential notch having there notch root radii), the concept of Notch Fracture Mechanics was applied. Volumetric fracture criterion with two parameters, effective stress and effective distance, was developed. The goal of the work was to quantify the influence of notch radius on transition temperature and notch fracture toughness, and, in addition, to present jointly the role of both these parameters in fracture behaviour.
In the case of the studied cast steel with a low yield stress (375 MPa), effective distance is 3 to 4 times longer than the Creager's effective distance (half of notch radius). The transition region and temperatures are shifted to higher values when notch radius decreases. At temperature higher than a temperature called plateau temperature Tp dactile filure appears. The Tp temperature is sensitive to nothe radius being affected by stress triaxiality. It is possible to define a notch sensitivity compensated temperature T* = √ρ/ρc. In the transition regime, critical notch stress intensity factor varies linearly with T*. and Obsahuje seznam literatury