96 research outputs found
Can management intensity be more important than environmental factors? A case study along an extreme elevation gradient from central Italian cereal fields
This paper aims to assess the importance of environmental and management factors determining the weed species
composition along a strong elevation gradient. A total of 76 cereal fields (39 low input and 37 intensively managed) were
sampled along an elevation gradient in central Italy. Explanatory variables were recorded for each field to elucidate the role of
large-scale spatial trends, of site-specific abiotic environmental conditions and of field management characters. Redundancy
analysis was used to assess the relative importance of each environmental variable in explaining the variation in species
composition. Our results indicate that variation in weed species composition is strongly determined by altitude, mean annual
precipitation, mean annual temperature and also by soil characteristics. However, the level of intensification proved to be the
most influential variable. There was a significant difference in species richness and composition between low-input and
intensively managed fields. Intensification leads to considerable species loss at both lower and higher elevations. Low-input
fields had 296 species in total, while intensively managed fields had only 196
Composition and Diversity of Lawn Flora in Differently Managed Village Yards – A Case Study from Southwestern Hungary
Properties of the Liquid-Vapor Interface of Acetone-Water Mixtures. A Computer Simulation and ITIM Analysis Study
Molecular dynamics simulations of the liquid-vapor interface of acetone-water mixtures of different compositions, covering the entire composition range have been performed on the canonical (N, V, T) ensemble at 298 K, using a model combination that excellently describes the mixing properties of these compounds. The properties of the intrinsic liquid surfaces have been analyzed in terms of the Identification of the Truly Interfacial Molecules (ITIM) method. Thus, the composition, width, roughness, and separation of the subsurface molecular layers, as well as self-association, orientation, and dynamics of exchange with the bulk phase of the surface molecules have been analyzed in detail. Our results show that acetone molecules are strongly adsorbed at the liquid surface, and this adsorption extends to several molecular layers. Like molecules in the surface layer are found to form relatively large lateral self-associates. The effect of the vicinity of the vapor phase on a number of properties of the liquid phase vanishes beyond the first molecular layer, with the second subsurface layer already part of the bulk liquid phase in these respects. The orientational preferences of the surface molecules are governed primarily by the dipole-dipole interaction of the neighboring acetone molecules, and hydrogen bonding interaction of the neighboring acetone-water pairs. (Figure Presented). © 2015 American Chemical Society
Relating Ambrosia artemisiifolia and other weeds to the management of Hungarian sunflower crops
The utility of the “Arable Weeds and Management in Europe” database: Challenges and opportunities of combining weed survey data at a European scale
Over the last 30 years many studies have surveyed weed vegetation on arable land. The “Arable Weeds and Management in Europe” (AWME) database is a collection of 36 of these surveys and the associated management data. Here we review the challenges associated with combining disparate datasets and explore some of the opportunities for future research that present themselves thanks to the advent of the AWME database.
We present three case studies repeating previously published national scale analyses with data from a larger spatial extent. We demonstrate that i) the standardisation of abundance data to a common measure, prior to the analysis of the combined dataset, has little impact on the outcome of the analyses, ii) the increased length of environmental or management gradients allows for greater confidence in conclusions, iii) the main conclusions of analyses done at different spatial extents remain consistent. These case studies demonstrate the utility of a Europe-wide weed survey database, for clarifying or extending results obtained from studies at smaller scales. This Europe-wide data collection offers many more opportunities for analysis that could not be addressed in smaller datasets; including questions about the effects of climate change, macro-ecological and biogeographical issues related to weed diversity as well as the dominance or rarity of specific weeds in Europe
Intravesical Treatments of Bladder Cancer: Review
For bladder cancer, intravesical chemo/immunotherapy is widely used as adjuvant therapies after surgical transurethal resection, while systemic therapy is typically reserved for higher stage, muscle-invading, or metastatic diseases. The goal of intravesical therapy is to eradicate existing or residual tumors through direct cytoablation or immunostimulation. The unique properties of the urinary bladder render it a fertile ground for evaluating additional novel experimental approaches to regional therapy, including iontophoresis/electrophoresis, local hyperthermia, co-administration of permeation enhancers, bioadhesive carriers, magnetic-targeted particles and gene therapy. Furthermore, due to its unique anatomical properties, the drug concentration-time profiles in various layers of bladder tissues during and after intravesical therapy can be described by mathematical models comprised of drug disposition and transport kinetic parameters. The drug delivery data, in turn, can be combined with the effective drug exposure to infer treatment efficacy and thereby assists the selection of optimal regimens. To our knowledge, intravesical therapy of bladder cancer represents the first example where computational pharmacological approach was used to design, and successfully predicted the outcome of, a randomized phase III trial (using mitomycin C). This review summarizes the pharmacological principles and the current status of intravesical therapy, and the application of computation to optimize the drug delivery to target sites and the treatment efficacy
European pollen-based REVEALS land-cover reconstructions for the Holocene: methodology, mapping and potentials
Quantitative reconstructions of past land cover are necessary to determine the processes involved in climate-human-land-cover interactions. We present the first temporally continuous and most spatially extensive pollen-based land-cover reconstruction for Europe over the Holocene (last 11 700 cal yr BP). We describe how vegetation cover has been quantified from pollen records at a 1 degrees x 1 degrees spatial scale using the "Regional Estimates of VEgetation Abundance from Large Sites" (REVEALS) model. REVEALS calculates estimates of past regional vegetation cover in proportions or percentages. REVEALS has been applied to 1128 pollen records across Europe and part of the eastern Mediterranean-Black Sea-Caspian corridor (30-75 degrees N, 25 degrees W-50 degrees E) to reconstruct the percentage cover of 31 plant taxa assigned to 12 plant functional types (PFTs) and 3 land-cover types (LCTs). A new synthesis of relative pollen productivities (RPPs) for European plant taxa was performed for this reconstruction. It includes multiple RPP values (>= 2 values) for 39 taxa and single values for 15 taxa (total of 54 taxa). To illustrate this, we present distribution maps for five taxa (Calluna vulgaris, Cerealia type (t)., Picea abies, deciduous Quercus t. and evergreen Quercus t.) and three land-cover types (open land, OL; evergreen trees, ETs; and summer-green trees, STs) for eight selected time windows. The reliability of the REVEALS reconstructions and issues related to the interpretation of the results in terms of landscape openness and human-induced vegetation change are discussed. This is followed by a review of the current use of this reconstruction and its future potential utility and development. REVEALS data quality are primarily determined by pollen count data (pollen count and sample, pollen identification, and chronology) and site type and number (lake or bog, large or small, one site vs. multiple sites) used for REVEALS analysis (for each grid cell). A large number of sites with high-quality pollen count data will produce more reliable land-cover estimates with lower standard errors compared to a low number of sites with lower-quality pollen count data. The REVEALS data presented here can be downloaded from https://doi.org/10.1594/PANGAEA.937075 (Fyfe et al., 2022)
Thermodynamics of Mixing Water with Dimethyl Sulfoxide, as Seen from Computer Simulations
- …
