Karyological and morphological variations within the genus Dysphania (Chenopodiaceae) in Bulgaria

The karyological and morphological variability of species from the genus Dysphania were studied. The results demonstrated that genus Dysphania is represented in Bulgaria by five species: Dysphania ambrosioides, D. multifida, D. botrys, D. schraderiana and D. pumilio. The first two species are tetraploids with chromosome number 2n = 32 for D. ambrosioides and 2n = 36 for D. multifida. The remaining three species are diploids with 2n = 18. The results from statistical analysis demonstrated that the main source of phenotype variation in the species is the interpopulation variation. The specific characters which allowed their recognition are themorphological characteristics of the perianth lobes, the upper leaves and the seeds. The distinction between D. multifida, D. ambrosioides and D. schraderiana is based on differences in the quantitative traits, while in D. botrys and D. pumilio qualitative traits are also important. The basic evolutionary mechanisms are polyploidy and diploidy.Atendency towards reduction in the size of generative organs and the number of perianth lobes was found

The intertropical convergence zone modulates intense hurricane strikes on the western North Atlantic margin

© The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Scientific Reports 6 (2016): 21728, doi:10.1038/srep21728Most Atlantic hurricanes form in the Main Development Region between 9°N to 20°N along the northern edge of the Intertropical Convergence Zone (ITCZ). Previous research has suggested that meridional shifts in the ITCZ position on geologic timescales can modulate hurricane activity, but continuous and long-term storm records are needed from multiple sites to assess this hypothesis. Here we present a 3000 year record of intense hurricane strikes in the northern Bahamas (Abaco Island) based on overwash deposits in a coastal sinkhole, which indicates that the ITCZ has likely helped modulate intense hurricane strikes on the western North Atlantic margin on millennial to centennial-scales. The new reconstruction closely matches a previous reconstruction from Puerto Rico, and documents a period of elevated intense hurricane activity on the western North Atlantic margin from 2500 to 1000 years ago when paleo precipitation proxies suggest that the ITCZ occupied a more northern position. Considering that anthropogenic warming is predicted to be focused in the northern hemisphere in the coming century, these results provide a prehistoric analog that an attendant northern ITCZ shift in the future may again return the western North Atlantic margin to an active hurricane interval.This research was supported by NSF Awards: OCE-1519578, OCE-1356708, BCS-1118340

A qualitative and quantitative model for climate-driven lake formation on carbonate platforms based on examples from the Bahamian archipelago

Lakes on carbonate platform islands such as the Bahamas display wide variability in morphometry, chemistry, and fauna. These parameters are ultimately driven by climate, sea level, and carbonate accumulation and dissolution. The authors propose a model that integrates climatological, geomorphological, and stratigraphic frameworks to understand processes of carbonate-hosted lake formation and limnological characteristics in modern day environments, with applications to carbonate lake sedimentary records. Fifty-two lakes from San Salvador Island and Eleuthera, Bahamas, were examined for water chemistry, basin morphology, conduit development, conductivity, and major ions. Using non-metric, multi-dimensional scaling ordination methods, the authors derived a model dividing lakes into either constructional or destructional formational modes. Constructional lakes were further divided into pre-highstand and highstand types based on whether their formation occurred during a marine regressive or transgressive phase. Destructional lakes are created continually by dissolution of bedrock at fresh/saline water interfaces and their formation is therefore related to changing climate and sea level. This model shows that lake formation is influenced by the hydrologic balance associated with climatic conditions that drives karst dissolution as well as the deposition of aeolian dune ridges that isolate basins due to sea-level fluctuations. It allows for testing and examining the climatic and hydrologic regime as related to carbonate accumulation and dissolution through time, and for an improved understanding of lake sensitivity and response to climate as preserved in the lacustrine sedimentary record

Autogenous deformation and relative humidity - Concrete with Aalborg Portland cement and fly ash

-This report summarizes the results from a series of experiments carried out in 7 new dilations rigs measuring autogenous deformation in concrete. The intention was to find a relation between autogenous deformation and relative humidity in three different mixes with three different binders. Another objective was to compare and verify the measurements of the new test rigs with corresponding samples tested according to SINTEF’s standardized shrinkage test method, which is described in KS 14-05-04-117.   Three different mixtures were used; one with Portland cement only (Portland cement, class CEM I 52,5 N), one with the same Portland cement and 5,2 % silica by cement weight and the third with the Portland cement and 50 % fly ash by cement weight. Three specimens (100×100×500 mm) were cast from each mixture; two in the new dilation rigs and one for SINTEF’s standard shrinkage test method. In addition, a specimen for measuring relative humidity (% RH) was cast from each mixture. Data from the measurements of deformation and relative humidity were collected in order to map the relation between autogenous deformation and relative humidity at certain concrete ages.   Autogenous deformation was measured with LVDTs (electrical transformers commonly used for measuring linear displacement) in the new Dilation Rigs. To measure relative humidity, a VAISALA Concrete Humidity Measurement System was used. All tests were performed in temperature conditioned environments, and a JULABO FP33 was used to regulate the temperature development in the concrete. Deformation of the reference specimens, were measured by the SINTEF standard shrinkage test method.   Some expected results of the concrete were confirmed during the experiments. Fly ash retards the heat development in the concrete, and further the hardening process. The self-desiccation of the concrete slows down, and seems to result in a higher relative humidity for a longer period.   Considering the results from the new rigs towardsThis report summarizes the results from a series of experiments carried out in 7 new dilations rigs measuring autogenous deformation in concrete. The intention was to find a relation between autogenous deformation and relative humidity in three different mixes with three different binders. Another objective was to compare and verify the measurements of the new test rigs with corresponding samples tested according to SINTEF’s standardized shrinkage test method, which is described in KS 14-05-04-117.   Three different mixtures were used; one with Portland cement only (Portland cement, class CEM I 52,5 N), one with the same Portland cement and 5,2 % silica by cement weight and the third with the Portland cement and 50 % fly ash by cement weight. Three specimens (100×100×500 mm) were cast from each mixture; two in the new dilation rigs and one for SINTEF’s standard shrinkage test method. In addition, a specimen for measuring relative humidity (% RH) was cast from each mixture. Data from the measurements of deformation and relative humidity were collected in order to map the relation between autogenous deformation and relative humidity at certain concrete ages.   Autogenous deformation was measured with LVDTs (electrical transformers commonly used for measuring linear displacement) in the new Dilation Rigs. To measure relative humidity, a VAISALA Concrete Humidity Measurement System was used. All tests were performed in temperature conditioned environments, and a JULABO FP33 was used to regulate the temperature development in the concrete. Deformation of the reference specimens, were measured by the SINTEF standard shrinkage test method.   Some expected results of the concrete were confirmed during the experiments. Fly ash retards the heat development in the concrete, and further the hardening process. The self-desiccation of the concrete slows down, and seems to result in a higher relative humidity for a longer period.   Considering the results from the new rigs toward

Autogenous deformation and relative humidity - Concrete with Aalborg Portland cement and fly ash

This report summarizes the results from a series of experiments carried out in 7 new dilations rigs measuring autogenous deformation in concrete. The intention was to find a relation between autogenous deformation and relative humidity in three different mixes with three different binders. Another objective was to compare and verify the measurements of the new test rigs with corresponding samples tested according to SINTEF’s standardized shrinkage test method, which is described in KS 14-05-04-117.   Three different mixtures were used; one with Portland cement only (Portland cement, class CEM I 52,5 N), one with the same Portland cement and 5,2 % silica by cement weight and the third with the Portland cement and 50 % fly ash by cement weight. Three specimens (100×100×500 mm) were cast from each mixture; two in the new dilation rigs and one for SINTEF’s standard shrinkage test method. In addition, a specimen for measuring relative humidity (% RH) was cast from each mixture. Data from the measurements of deformation and relative humidity were collected in order to map the relation between autogenous deformation and relative humidity at certain concrete ages.   Autogenous deformation was measured with LVDTs (electrical transformers commonly used for measuring linear displacement) in the new Dilation Rigs. To measure relative humidity, a VAISALA Concrete Humidity Measurement System was used. All tests were performed in temperature conditioned environments, and a JULABO FP33 was used to regulate the temperature development in the concrete. Deformation of the reference specimens, were measured by the SINTEF standard shrinkage test method.   Some expected results of the concrete were confirmed during the experiments. Fly ash retards the heat development in the concrete, and further the hardening process. The self-desiccation of the concrete slows down, and seems to result in a higher relative humidity for a longer period.   Considering the results from the new rigs toward