Effects of Category Aggregation on Land Change Simulation Based on Corine Land Cover Data

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Spring-block approach for nanobristle patterns

A two dimensional spring-block type model is used to model capillarity driven self-organization of nanobristles. The model reveals the role of capillarity and van der Waals forces in the pattern formation mechanism. By taking into account the relevant interactions several type of experimentally observed patterns are qualitatively well reproduced. The model offers the possibility to generate on computer novel nanobristle based structures, offering hints for designing further experiments.Comment: 6 pages, 6 figure

Mathematical modeling of char reactivity in Ar-O2 and CO2-O2 mixtures

The kinetics of the coal char + O2 reaction was studied by thermogravimetry. Low sample masses were employed to ensure an approximate kinetic regime. Special emphasis was placed on clarifying how the recirculation of the flue gases (i.e. the presence of a high amount of CO2 at low O2 concentrations) affects the reactivity. The ambient gas concentrations varied from 100% O2 to 5% O2 in CO2 or Ar. A semi-empirical model is presented which can approximate the reactivity changes during the conversion and takes into account the heterogeneity of the samples. A least squares evaluation procedure resulted in a good fit to the experimental data over a wide variety of temperature programs and ambient gas concentrations. The overall burn-off time of the samples varied from eight minutes to three hours depending on the experimental conditions. The reaction rate was found to be proportional to the O2 concentration of the ambient gas and was not influenced by the presence of high amounts of CO2. The reaction started with a sharp acceleration period indicating an initial activation of the char surface

O Efeito Sul: reflexões críticas sobre o engajamento do Brasil com Estados frágeis

Frequentemente, em um contexto sul-sul ou de cooperação triangular, países que não pertencem à OCDE, como o Brasil,estão adotando um papel proeminente de provedores de auxílio, voltando-se, inclusive, para os chamados Estados frágeis.Os recentes esforços brasileiros para a promoção de desenvolvimento em outros países baseiam-se, fundamentalmente,em princípios de solidariedade, afinidades culturais e em uma experiência comum como país recipiente de ajuda. Asagências públicas e não governamentais brasileiras estão cada vez mais envolvidas na exportação e adaptação detecnologias sociais domésticas para Estados frágeis e também estáveis, incluindo Angola, Guatemala, Guiné-Bissau,Haiti, Moçambique, Suriname e Timor-Leste. Inevitavelmente guiada por prioridades geopolíticas, a ajuda brasileiraparece motivada no mínimo igualmente pelas necessidades encontradas em Dili, Maputo e Porto Príncipe e pelasprioridades genéricas estabelecidas em Paris, Washington e Brasília. Este texto analisa o fenômeno emergente do EfeitoSul e algumas de suas implicações para o engajamento em Estados frágeis no século XXI

Bulk and surface sensitivity of a resonant waveguide grating imager

We report the assessment of the sensitivity of a microplate-compatible resonant waveguide grating imager. The sensitivity to bulk refractive index changes was determined using a serial dilution of glycerol solution with the help of a refractometer. The surface sensitivity was examined using layer-by-layer polyelectrolyte films in conjunction with optical waveguide lightmode spectroscopy and characterized by the binding of acetazolamide to immobilized carbonic anhydrase under microfluidics. The results suggest that the imager has a limit of detection down to 2.2 × 10−6 for refractive index change and 0.078 ng/cm2 for the adsorbed mass. © 2014 AIP Publishing LL

Automated single cell sorting and deposition in submicroliter drops

Automated manipulation and sorting of single cells are challenging, when intact cells are needed for further investigations, e.g., RNA or DNA sequencing. We applied a computer controlled micropipette on a microscope admitting 80 PCR (Polymerase Chain Reaction) tubes to be filled with single cells in a cycle. Due to the Laplace pressure, fluid starts to flow out from the micropipette only above a critical pressure preventing the precise control of drop volume in the submicroliter range. We found an anomalous pressure additive to the Laplace pressure that we attribute to the evaporation of the drop. We have overcome the problem of the critical dropping pressure with sequentially operated fast fluidic valves timed with a millisecond precision. Minimum drop volume was 0.4-0.7 μl with a sorting speed of 15-20 s per cell. After picking NE-4C neuroectodermal mouse stem cells and human primary monocytes from a standard plastic Petri dish we could gently deposit single cells inside tiny drops. 94 ± 3% and 54 ± 7% of the deposited drops contained single cells for NE-4C and monocytes, respectively. 7.5 ± 4% of the drops contained multiple cells in case of monocytes. Remaining drops were empty. Number of cells deposited in a drop could be documented by imaging the Petri dish before and after sorting. We tuned the adhesion force of cells to make the manipulation successful without the application of microstructures for trapping cells on the surface. We propose that our straightforward and flexible setup opens an avenue for single cell isolation, critically needed for the rapidly growing field of single cell biology. © 2014 AIP Publishing LLC

Microbial stowaways: Waterbirds as dispersal vectors of aquatic pro‐ and microeukaryotic communities

Aim: Waterbirds are important dispersal vectors of multicellular organisms; however, no study to date has focused on their potential role in dispersing aquatic microbial communities. We explicitly studied endozoochory of prokaryotes and unicellular mi- croeukaryotes by waterbirds using DNA metabarcoding. By directly comparing the dispersed set of organisms to the source pool of a natural metacommunity, we aimed at a realistic estimate of the importance of waterbird zoochory for natural microbial communities. Location: Temporary saline soda pans in Austria and Hungary. Taxon: Prokaryotes and unicellular microeukaryotes. Methods: In 2017 and 2018, water samples were collected from a network of 25 tem- porary ponds along with fresh droppings of five waterbird species including the domi- nant greylag goose (Anser anser). Prokaryotic and microeukaryotic communities were identified via 16S and 18S rRNA gene amplicon sequencing. After quality filtering of sequence reads, pro- and microeukaryotic amplicon sequence variant (ASV) composi- tions were compared between the aquatic and dropping samples, across years and waterbird species. Results: 28% of the dominant aquatic prokaryotic and 19% of the microeukaryotic ASVs were transported by A. anser. ASV richness was lower, but compositional varia- tion was higher in A. anser droppings than in aquatic communities, probably resulting from stochastic pick-up from multiple aquatic habitats. The composition of prokary- otic ASVs in bird droppings differed among the 2 years and reflected the actual aquatic communities. The dispersed set of microbes were largely similar among the waterbird species except for the planktivore filter- feeder northern shoveler (Spatula clypeata), which dispersed more microeukaryotes than the other waterbirds. Main conclusions: Using an amplicon sequencing approach to characterize aquatic microorganisms in waterbird droppings and in the associated environment, our study provides strong evidence for endozoochory of natural communities. These results imply that waterbirds may be crucial in maintaining ecological connectivity between aquatic habitats at the level of microbial communities

Intensity Analysis and the Figure of Merit’s components for assessment of a Cellular Automata – Markov simulation model

Some popular metrics to evaluate land change simulation models are misleading. Therefore, land change scientists have called for the development of methods to evaluate various aspects of modelling applications. This article answers the call by giving novel methods to compare three types of land change: 1) reference change during the calibration time interval, 2) simulation change during the validation time interval, and 3) reference change during the validation time interval. We compare these changes by using Intensity Analysis’ three levels and the Figure of Merit’s four components: Misses, Hits, Wrong Hits and False Alarms. We illustrate the concepts by applying a Cellular Automata – Markov land change model to a case study in northeast Hungary. We used reference maps of five land categories to calibrate the model during 2000–2006, then to validate the simulation during 2006–2012. Intensity Analysis’ time interval level shows that the simulation change and the reference change decelerated from 2000–2006 to 2006–2012. Intensity Analysis’ category level shows that the simulation losses were less than what a pure Markov chain would have dictated. Intensity Analysis’ transition level shows that the model’s Markov algorithm simulated correctly that the gain of Forest targeted Agriculture and Wetland. The Figure of Merit’s components reveals more allocation error than quantity error. Our collection of metrics show that more error derived from the Cellular Automata algorithm than from the Markov algorithm. We recommend that scientists use Intensity Analysis and the Figure of Merit’s components to reveal various fundamental aspects of modelling applications