Pre-study of Dynamic Amplification Factor for Existing Road Bridges

The Swedish Road network has, since 2018, been divided into four bearing capacity classes (BKs)—BK1–BK4. The heaviest allowed gross vehicle weight increased when BK4 was introduced, from 64 tonnes (BK1) to 74 tonnes (BK4). The Swedish Transport Administration aims, by 2025, to classify 60 % of the strategic road network for the heavy transport industry as BK4, increasing to 70–80 % by 2029. However, to reach these goals, it is estimated that over 700 bridges will need to be strengthened or replaced.This study, using a site-specific investigation to calculate the assessment dynamic ratio (ADR), showed that some of these bridges could be upgraded to BK4. A review of the literature indicated that light vehicles tend to have high dynamic amplification factors (DAFs), but light vehicles do not have critical load effects and are therefore not relevant from a design perspective. Instead, heavy vehicles are critical for the design. Both experimental and analytical investigations have shown that heavy gross vehicle weights result in low DAF values.This report proposes effective ways to collect site-specific dynamic traffic load information and a methodology to produce site-specific dynamic allowances using both experimental measurements and numeric models. It also explains how this methodology can be adopted by transportation agencies to study bridges along transport corridors.Findings from the pre-study have resulted in the following research proposals: sitespecific field measurements to quantify DAFs, guidelines for numerical modelling of vehicle–bridge interactions (VBIs), DAF for each limit state, three–dimensional analysis of VBIs, the introduction of gross vehicle weight into DAF equations, and pilot tests of proposed frameworks for transport corridors. The authors believe that several topics can be covered within the framework of a PhD project

An autocrine sphingosine-1-phosphate signaling loop enhances NF-kappaB-activation and survival

Peer reviewe

Ethyl 3,6-di-O-benzyl-2-de­oxy-N-phthalimido-1-thio-β-d-glucopyran­oside

In the title compound, C30H31NO6S, the plane of the N-phthalimido group is nearly orthogonal to the least-squares plane of the sugar ring (defined by atoms C2, C3, C5 and O5 using standard glucose nomenclature), making a dihedral angle of 72.8 (1)°. The thio­ethyl group has the exo-anomeric conformation. The hy­droxy group forms an inter­molecular hydrogen bond to the O atom in the sugar ring, generating [100] chains. There are four close π–π contacts with centroid–centroid distances less than 4.0 Å, all with dihedral angles between the inter­acting π systems of only ≃ 8°, supporting energetically favourable stacking inter­actions

Modification of permeability transition pore arginine(s) by phenylglyoxal derivatives in isolated mitochondria and mammalian cells. Structure-function relationship of arginine ligands.

Methylglyoxal and synthetic glyoxal derivatives react covalently with arginine residue(s) on the mitochondrial permeability transition pore (PTP). In this study, we have investigated how the binding of a panel of synthetic phenylglyoxal derivatives influences the opening and closing of the PTP. Using both isolated mitochondria and mammalian cells, we demonstrate that the resulting arginine-phenylglyoxal adduct can lead to either suppression or induction of permeability transition, depending on the net charge and hydrogen bonding capacity of the adduct. We report that phenylglyoxal derivatives that possess a net negative charge and/or are capable of forming hydrogen bonds induced permeability transition. Derivatives that were overall electroneutral and cannot form hydrogen bonds suppressed permeability transition. When mammalian cells were incubated with low concentrations of negatively charged phenylglyoxal derivatives, the addition of oligomycin caused a depolarization of the mitochondrial membrane potential. This depolarization was completely blocked by cyclosporin A, a PTP opening inhibitor, indicating that the depolarization was due to PTP opening. Collectively, these findings highlight that the target arginine(s) is functionally linked with the opening/closing mechanism of the PTP and that the electric charge and hydrogen bonding of the resulting arginine adduct influences the conformation of the PTP. These results are consistent with a model where the target arginine plays a role as a voltage sensor

Latitude, temperature, and habitat complexity predict predation pressure in eelgrass beds across the Northern Hemisphere

Latitudinal gradients in species interactions are widely cited as potential causes or consequences of global patterns of biodiversity. However, mechanistic studies documenting changes in interactions across broad geographic ranges are limited. We surveyed predation intensity on common prey (live amphipods and gastropods) in communities of eelgrass (Zostera marina) at 48 sites across its Northern Hemisphere range, encompassing over 370 of latitude and four continental coastlines. Predation on amphipods declined with latitude on all coasts but declined more strongly along western ocean margins where temperature gradients are steeper. Whereas in situ water temperature at the time of the experiments was uncorrelated with predation, mean annual temperature strongly positively predicted predation, suggesting a more complex mechanism than simple increased metabolic activity at the time of predation. This large-scale biogeographic pattern was modified by local habitat characteristics; predation declined with higher shoot density both among and within sites. Predation rates on gastropods, by contrast, were uniformly low and varied little among sites. The high replication and geographic extent of our study not only provides additional evidence to support biogeographic variation in intensity, but also insight into the mechanisms that relate temperature and biogeographic gradients in species interactions

The biogeography of community assembly: latitude and predation drive variation in community trait distribution in a guild of epifaunal crustaceans

While considerable evidence exists of biogeographic patterns in the intensity of species interactions, the influence of these patterns on variation in community structure is less clear. Studying how the distributions of traits in communities vary along global gradients can inform how variation in interactions and other factors contribute to the process of community assembly. Using a model selection approach on measures of trait dispersion in crustaceans associated with eelgrass (Zostera marina) spanning 30 degrees of latitude in two oceans, we found that dispersion strongly increased with increasing predation and decreasing latitude. Ocean and epiphyte load appeared as secondary predictors; Pacific communities were more overdispersed while Atlantic communities were more clustered, and increasing epiphytes were associated with increased clustering. By examining how species interactions and environmental filters influence community structure across biogeographic regions, we demonstrate how both latitudinal variation in species interactions and historical contingency shape these responses. Community trait distributions have implications for ecosystem stability and functioning, and integrating large-scale observations of environmental filters, species interactions and traits can help us predict how communities may respond to environmental change.info:eu-repo/semantics/publishedVersio

A Pleistocene legacy structures variation in modern seagrass ecosystems

Distribution of Earth's biomes is structured by the match between climate and plant traits, which in turn shape associated communities and ecosystem processes and services. However, that climate-trait match can be disrupted by historical events, with lasting ecosystem impacts. As Earth's environment changes faster than at any time in human history, critical questions are whether and how organismal traits and ecosystems can adjust to altered conditions. We quantified the relative importance of current environmental forcing versus evolutionary history in shaping the growth form (stature and biomass) and associated community of eelgrass (Zostera marina), a widespread foundation plant of marine ecosystems along Northern Hemisphere coastlines, which experienced major shifts in distribution and genetic composition during the Pleistocene. We found that eelgrass stature and biomass retain a legacy of the Pleistocene colonization of the Atlantic from the ancestral Pacific range and of more recent within-basin bottlenecks and genetic differentiation. This evolutionary legacy in turn influences the biomass of associated algae and invertebrates that fuel coastal food webs, with effects comparable to or stronger than effects of current environmental forcing. Such historical lags in phenotypic acclimatization may constrain ecosystem adjustments to rapid anthropogenic climate change, thus altering predictions about the future functioning of ecosystems.This work was supported by the US NSF (OCE-1031061, OCE-1336206, OCE0-1336741, OCE-1336905) and the Smithsonian Institution. F.T. was supported by José Castillejo Award CAS14/00177. A.H.E. was supported by the FCT (Foundation for Science and Technology) through Project UIDB/04326/2020 and Contract CEECINST/00114/2018. This is Contribution 106 from the Smithsonian’s MarineGEO and Tennenbaum Marine Observatories Network and Contribution 4105 of the Virginia Institute of Marine Science, College of William & Mary