Investigation of reinforced concrete columns with recessed longitudinal rods without transverse reinforcement

The article deals with the feasibility of a significant increase in the thickness of the protective layer of longitudinal rods in compressed reinforced concrete columns. We describe the experimental data of the work of the reinforced concrete columns with recessed longitudinal reinforcement without transverse reinforcement. We provide a method for calculation of such structures and optimum parameters of the thickness of the protective layer on the criterion of maximum critical efforts

Juveniles of pink and chum salmon in the Iska River (Sakhalin Bay, Okhotsk Sea) in the fresh-water period

Juveniles of pink and chum salmon are investigated in the Iska River flowing into the Okhotsk Sea. The pink juveniles begin their seaward migration in May, with the ice melting, the migration lasts about 40 days, approximately from May 20 to July 5. The seaward migration of chum juveniles begins in the same time but ends in 5-10 days later. The portion of pink salmon fry with the remains of yolk sac is 82-94 %; even in the end of their migration it is rather high, up to 76 %. This species juveniles begin to feed in the river, in particular in «dry» years, the portion of feeding fry increases with disappearance of the yolk sac up to 78 % (by the stomach fullness). Both pink and chum juveniles migrate at night only. Hydrological conditions influence on the timing of migration: it is close to normal dates in conditions of high water level and strong water flow but delayed in conditions of low water discharge (that’s why the portion of juveniles feeding in the river is higher in those years). Year-to-year dynamics of the juveniles and spawners abundance is traced for the 1951-2012. The pink salmon escapement to the Iska changed from 11.0 · 103 (in 2004) to 1344.4 · 103 (in 1958) ind., on average 280.0 · 103 ind. for even years and from 22.7 · 103 (in 1959) to 2005.8 · 103 (in 2007) ind., on average 372.9 · 103 ind. for odd years. The number of pink salmon downstream migrants changed from 0.8 · 106 (in 1954) to 40.9 · 106 (in 1964), on average 10.9 · 106 ind. for even years and from 1.0 · 106 (in 2005) to 41.8 · 106 (in 1957), on average 8.9 · 106 ind. for odd years

On the Origin and Trigger of the Notothenioid Adaptive Radiation

Adaptive radiation is usually triggered by ecological opportunity, arising through (i) the colonization of a new habitat by its progenitor; (ii) the extinction of competitors; or (iii) the emergence of an evolutionary key innovation in the ancestral lineage. Support for the key innovation hypothesis is scarce, however, even in textbook examples of adaptive radiation. Antifreeze glycoproteins (AFGPs) have been proposed as putative key innovation for the adaptive radiation of notothenioid fishes in the ice-cold waters of Antarctica. A crucial prerequisite for this assumption is the concurrence of the notothenioid radiation with the onset of Antarctic sea ice conditions. Here, we use a fossil-calibrated multi-marker phylogeny of nothothenioid and related acanthomorph fishes to date AFGP emergence and the notothenioid radiation. All time-constraints are cross-validated to assess their reliability resulting in six powerful calibration points. We find that the notothenioid radiation began near the Oligocene-Miocene transition, which coincides with the increasing presence of Antarctic sea ice. Divergence dates of notothenioids are thus consistent with the key innovation hypothesis of AFGP. Early notothenioid divergences are furthermore congruent with vicariant speciation and the breakup of Gondwana

Molecular pedomorphism underlies craniofacial skeletal evolution in Antarctic notothenioid fishes

Background Pedomorphism is the retention of ancestrally juvenile traits by adults in a descendant taxon. Despite its importance for evolutionary change, there are few examples of a molecular basis for this phenomenon. Notothenioids represent one of the best described species flocks among marine fishes, but their diversity is currently threatened by the rapidly changing Antarctic climate. Notothenioid evolutionary history is characterized by parallel radiations from a benthic ancestor to pelagic predators, which was accompanied by the appearance of several pedomorphic traits, including the reduction of skeletal mineralization that resulted in increased buoyancy. Results We compared craniofacial skeletal development in two pelagic notothenioids, Chaenocephalus aceratus and Pleuragramma antarcticum, to that in a benthic species, Notothenia coriiceps, and two outgroups, the threespine stickleback and the zebrafish. Relative to these other species, pelagic notothenioids exhibited a delay in pharyngeal bone development, which was associated with discrete heterochronic shifts in skeletal gene expression that were consistent with persistence of the chondrogenic program and a delay in the osteogenic program during larval development. Morphological analysis also revealed a bias toward the development of anterior and ventral elements of the notothenioid pharyngeal skeleton relative to dorsal and posterior elements. Conclusions Our data support the hypothesis that early shifts in the relative timing of craniofacial skeletal gene expression may have had a significant impact on the adaptive radiation of Antarctic notothenioids into pelagic habitats

Features of application of bimoment theory of V.Z. Vlasov in the calculations of reinforced concrete bar structures

Abstract In this paper, an adaptation variant of the “deformation model” is proposed for estimating the parameters of the stress-strain state of a reinforced concrete bar element with flexible discrete reinforcement, taking into account the deplanation of concrete and the features of contact interaction between reinforcement and concrete. Basic principles of the bimoment theory of solid rods of V.Z. Vlasov are used to assess concrete deplanation.</jats:p