Recent developments in computational design and digital fabrication with concrete enable the realization of freeform geometries that optimize material use. 3D Concrete extrusion Printing (3DCP) is ...presently one of the most utilized digital fabrication methods with concrete. The expected advantages of 3DCP result from shaping concrete without formwork and from placing material only where functionally required. Although these advantages were pointed out more than 20 years ago, it is difficult to find competitive examples and their usage in real buildings. Consequently, the nonspecific character of the process acts as a shortcoming by opening up extensive possibilities without a clear direction. This paper proposes an automated 3DCP prefabrication platform for customized columns. The process-specific parameters are, therefore, fine-tuned for high-quality products with diverse forms and textures. Additionally, this paper proposes an evaluation method for geometric complexity and identifies the types of column typologies that may benefit from a 3DCP prefabrication platform.
•A 3D concrete printing process is proposed for the prefabrication of bespoke columns.•This layered extrusion-based process uses a set on-demand material system.•The technology targets a concrete prefabrication plant.•The design methods focus on column typologies tailored for 3D concrete printing.•The 3D concrete printed columns are evaluated based on their geometric complexity.
•The range of the Andean grass Poa scaberula will be reduced under global warming.•Climatic factors are the main drivers of range reduction.•Global warming could drastically impact on the Andean ...grasslands.•Inclusion of elevation into the models decreased their performance.
Grasslands play an important ecological role and are the dominant landscape in the whole extent of the Andes and high elevation regions of South America. Climate change models indicate a strong impact on mountain systems. The climatic conditions of mountain systems are greatly influenced by topography and elevation. Poa scaberula Hook. f. is an Andean grass and its habitat may be threatened by climate change and human practices. Species distribution models, using bioclimatic variables, are often used to predict the future distribution and environmental requirements of species. In this study we prepared two bioclimatic models for P. scaberula using the Maxent algorithm, the first based on the inclusion of the variable elevation (E +) and the second on the exclusion of elevation (E-) to identify the main environmental variables for habitat suitability shift, to examine changes in the extent of the area of suitable habitat under current and future climate scenarios, and to project and quantify the spatial pattern of shifts in the areal extent of suitable habitat under future climate conditions. We then compared both projections and evaluate the contribution of the elevation variable in the performance of the models. We observed that the inclusion of elevation decreased the performance of the models. In models with omission of the elevation mean cold hardiness, temperature seasonality and annual mean temperature emerge as the critical factors shaping habitat suitability for P. scaberula. Under the low and higher concentration greenhouse gas emissions scenario, the range of the species may decrease as global warming intensifies. The information gained from this study should be an useful reference for development biogeographic studies and the impact of global warming on regions of high elevations, and contribute to implement conservation and management strategies for Andean grassland and high elevation grasslands.
Here we conduct research to understand the evolutionary history of a shrubby species known as Agarito (Berberis trifoliolata), an endemic species to the Chihuahuan Desert. We identify genetic ...signatures based on plastid DNA and AFLP markers and perform niche modelling and spatial connectivity analyses as well as niche modelling based on records in packrats to elucidate whether orogenic events such as mountain range uplift in the Miocene or the contraction/expansion dynamics of vegetation in response to climate oscillations in the Pliocene/Pleistocene had an effect on evolutionary processes in Agarito. Our results of current niche modelling and palaeomodelling showed that the area currently occupied by Berberis trifoliolata is substantially larger than it was during the Last Interglacial period and the Last Glacial Maximum. Agarito was probably confined to small areas in the Northeastern and gradually expanded its distribution just after the Last Glacial Maximum when the weather in the Chihuahuan Desert and adjacent regions became progressively warmer and drier. The most contracted range was predicted for the Interglacial period. Populations remained in stable areas during the Last Glacial Maximum and expanded at the beginning of the Holocene. Most genetic variation occured in populations from the Sierra Madre Oriental. Two groups of haplotypes were identified: the Mexican Plateau populations and certain Northeastern populations. Haplogroups were spatially connected during the Last Glacial Maximum and separated during interglacial periods. The most important prediction of packrat middens palaeomodelling lies in the Mexican Plateau, a finding congruent with current and past niche modelling predictions for agarito and genetic results. Our results corroborate that these climate changes in the Pliocene/Pleistocene affected the evolutionary history of agarito. The journey of agarito in the Chihuahuan Desert has been dynamic, expanding and contracting its distribution range and currently occupying the largest area in its history.
Abstract Soluble allelochemicals have generated great interest since they can be used for the biological control of pests, especially of weeds. However, few studies have evaluated the effectiveness ...of soluble compounds of exudates on germination in relation to exposure time. Here we evaluate the inhibitory effect of aqueous root, stem and leaf extracts of five South American species of Bothriochloa on the percentage of seed germination of four target species (lettuce, lovegrass, maize and wintergreen paspalum) over three exposure periods (48, 120 and 168 h). Aqueous extracts of the five Bothriochloa species inhibited germination; germination inhibition was strongly correlated with exposure time, with the longest treatment period (168 h) being the one of greatest inhibitory activity. Inhibitory activity differed among types of aqueous extracts. The suitable management of allelopathy might improve crop productivity and environmental protection through biologically friendly control of weeds.
Resumo Aleloquímicos solúveis têm gerado grande interesse, pois podem ser utilizados para o controle biológico de pragas, principalmente de plantas daninhas. No entanto, poucos estudos avaliaram a eficácia de compostos solúveis de exsudatos na germinação com relação ao tempo de exposição. Aqui, avaliamos o efeito inibitório de extratos aquosos de raízes, caules e folhas de cinco espécies sul-americanas de Bothriochloa na porcentagem de germinação de quatro espécies-alvo (alface, choro de capim, milho e paspalum verde-inverno) ao longo de três períodos de exposição (48, 120 and 168 h). Extratos aquosos das cinco espécies de Bothriochloa inibiram a germinação; a inibição da germinação foi fortemente correlacionada com o tempo de exposição, sendo o período de tratamento mais longo (168 h) o de maior atividade inibitória. A atividade inibitória diferiu entre os tipos de extratos aquosos. O manejo adequado da alelopatia pode melhorar a produtividade das culturas e a proteção ambiental através do controle biológico de ervas daninhas.
The South American Transition Zone (SATZ) is a biogeographic area in which not only orogeny (Andes uplift) and climate events (aridification) since the mid-Miocene, but also Quaternary glaciation ...cycles had an important impact on the evolutionary history of the local flora. To study this effect, we selected Munroa argentina, an annual grass distributed in the biogeographic provinces of Puna, Prepuna and Monte. We collected 152 individuals from 20 localities throughout the species' range, ran genetic and demographic analyses, and applied ecological niche modeling. Phylogenetic and population genetic analyses based on cpDNA and AFLP data identified three phylogroups that correspond to the previously identified subregions within the SATZ. Molecular dating suggests that M. argentina has inhabited the SATZ since approximately 3.4 (4.2-1.2) Ma and paleomodels predict suitable climate in these areas during the Interglacial period and the Last Glacial Maximum. We conclude that the current distribution of M. argentina resulted from the fragmentation of its once continuous range and that climate oscillations promoted ecological differences that favored isolation by creating habitat discontinuity.
•The land abandonment changes the ecosystem functions.•The major changes in ecosystem occurs the first two decades since abandonment.•Soil C and N contents and biological activity increase along ...chronosequence.•Grassland composition determines soil microbial activity.
Euro-Mediterranean countries have undergone radical changes in their traditional landscapes due to the abandonment of rural areas. Natural vegetation rapidly colonizes abandoned lands and cause changes in ecosystem functioning. Our main objective was to study how time since abandonment of vineyards influences the physical, chemical and biological properties of the soil and the vegetation composition and cover. In 2016, we selected a chronosequence of six abandoned vineyards (1, 3, 7, 11, 25 and 40 years), an active vineyard, and a plot of land that has not been used as a vineyard for at least the last 60 years. Soil physical-chemical variables, including the organic matter fractions and available nutrients, were analysed. To observe the variation in the biochemical properties of the soils, the activities of 11 enzymes were determined, relating to the main macronutrient cycles: carbon (C), nitrogen (N), phosphorous (P) and sulphur (S) cycling. Three sites (1 m2) were randomly established on each plot within the area occupied by annual grasslands, and species cover was estimated in order to obtain the species density and cover of plant functional traits. Our results showed that the abandonment caused major changes in the functioning of the ecosystems. Secondary succession in abandoned vineyards was characterized by a significant increase in plant species density and by changes in the composition of the annual grasslands, from an early brassicaceous community to a late cistaceous community. This was accompanied by an increase in soil TOC (0.38–1.78%) and TN (0.14 to 0.26 %) content, and the activity of most enzymes. These changes occurred more rapidly during the first two decades after abadonment.
Mountains support a great diversity of species and habitat types. Grasslands are the dominant landscape in the Andes and play an important ecological role. However, they are threatened by many ...factors, including climate change and human activities. The spatial distribution of species that compose, and the ecological and evolutionary factors that provide for the spatial biodiversity patterns, are little known. The largest Poa L. (Poaceae) genera are widely diversified and distributed in the Andes. In particular, P. scaberula Hook. f. shows great environmentally mediated phenotypic plasticity, and is distributed from North America to the tip of South America. However, the impact of environmental variables has on the spatial distribution of this species, remain largely unknown. Using high-resolution climatic data, herein we modeled the current suitable habitat for P. scaberula and identified the main climatic variables that best predict its potential distribution. In addition, we assess the species status in the predicted habitats through herbarium data and relate it with species distribution models. The models showed that P. scaberula has a suitable habitat of ca. 162.747 km2 along the Andes and high elevation regions. The most influential variables with a 68.5% contribution to the distribution of the species, particularly high elevation areas, included mean cold hardiness, water vapor pressure and temperature seasonality. The areas of greatest suitability with the highest occurrence of the species were identified geographically by the models. The present study provides useful information that can assist in the identification of areas where the species is most sensitive to different variables, including climate change and human activities and contributes in assessing the conservation status of Andean grassland at a regional scale.
Ecology; Environmental science; Plant biology; Biodiversity; Flora; Botany; Andean grass; Climatic variables; Grasslands; High elevation regions; South America; Global ecological change; Systems biology.
VKORC1 and CYP2C9 polymorphisms are used to predict the safe dose of oral anticoagulant therapy. A new variant of CYP4F2 (V433M) has recently been related to the required warfarin dose. We evaluated ...its influence in earliest response to acenocoumarol in 100 selected men who started anticoagulation (3 mg for 3 consecutive days). V433M genotype exerted a gene dosage-dependent effect on the decrease of factors II, VII, IX, and X in the earliest response to acenocoumarol, with homozygous 433V subjects being the most sensitive. Similarly, after the initiation of therapy, international normalized ratio also experienced a gene dosage-dependent effect (P = .015), and 433V subjects needed 4 mg/week less than 433M carriers to achieve a steady anticoagulation (P = .043). Multivariate linear regression analysis revealed a significant contribution of V433M polymorphism to variability of both early international normalized ratio value (R2 = 0.14) and dose requirements (R2 = 0.19). Our data underline the relevant role of CYP4F2 V433M polymorphism in the pharmacogenetics of coumarin anticoagulants.
The Andean Puna is an arid, high-elevation plateau in which plants such as grasses experience high abiotic stress and distinctive environmental conditions. We assessed colonization by arbuscular ...mycorrhizal fungi (AMF) and dark septate endophytes (DSE) in the roots of 20 native grass species and examined the relationship between root-associated fungi (AMF and DSE) as a function of the elevation of study sites, the photosynthetic pathways of the grass hosts, and the hosts' life cycles. In general, grasses were co-colonized by AMF and DSE and the colonization by AMF and DSE was not extensive. The extension of colonization of AMF and that of DSE were positively correlated, as were number of arbuscules and DSE colonization extension. The extension of AMF colonization differed among sites with different elevations, but DSE colonization was similar across sites. Overall, AMF and DSE patterns shifted as a function of elevation in most grass species, with no general trends observed with respect to host photosynthetic pathway or life cycle. In general, our observations differ from previous studies in the Northern Hemisphere. Variation among sites in AMF and DSE colonization was greater than variation that could be explained by the other factors considered here, suggesting a strong influence of environmental factors. We predict that both AMF and DSE may have established synergistic and beneficial associations with grasses in these distinctive and harsh ecosystems.
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