Postdocs reimagined Konstantinides, Nikolaos; Dinkins, Christina; Stewart, Martin P. ...
Science (American Association for the Advancement of Science),
07/2015, Volume:
349, Issue:
6243
Journal Article
With a model invertebrate animal, we have assessed the fate of magnetic nanoparticles in biologically relevant media, i.e., digestive juices. The toxic potential and the internalization of such ...nanoparticles by nontarget cells were also examined. The aim of this study was to provide experimental evidence on the formation of ..., ..., and ... ions from ... nanoparticles in the digestive juices of a model organism. Standard toxicological parameters were assessed. Cell membrane stability was tested with a modified method for measurement of its quality. Proton-induced X-ray emission and low energy synchrotron radiation X-ray fluorescence were used to study internalization and distribution of Co and Fe. ... ions were found to be more toxic than nanoparticles. We confirmed that ... ions accumulate in the hepatopancreas, but ... ions or ... nanoparticles are not retained in vivo. A model biological system with a terrestrial isopod is suited to studies of the potential dissolution of ions and other products from metal-containing nanoparticles in biologically complex media. (ProQuest: ... denotes formulae/symbols omitted.)
Recent publications have presented many successful usages of elements from information theory in adaptive systems training. Error-entropy has been proven to outperform mean squared error as a cost ...function in many artificially generated data sets, but still few applications to real world data have been published. In this paper, we design a neural network trained with error-entropy minimization criterion and use it for dynamical systems modeling on artificial as well as real world data. Performance of this neural network is compared against the mean squared error driven approach in terms of computational complexity, parameter optimization, and error probability densities.
Evolutionary Synthesis of Cellular Automata ZUPANC, Jernej; FILIPIC, Bogdan
Journal of computing and information technology,
06/2011, Volume:
19, Issue:
2
Journal Article, Paper
Peer reviewed
Open access
Synthesis of cellular automata is an important area of modeling and describing complex systems. Large amounts of combinations and candidate solutions render the usage of deterministic approaches ...impractical and thus non-deterministic optimization methods have to be employed. Two of the typical evolutionary approaches to synthesizing cellular automata are the evolution of a single automaton and a genetic algorithm that evolves a population of automata. The first approach, with addition of some heuristics, is known as the cellular programming algorithm. In this paper we address the second approach and develop a genetic algorithm that evolves a population of cellular automata. We test both approaches on the density classification task, which is one of the most widely studied computational problems in the context of evolving cellular automata. Comparison of the synthesized cellular automata demonstrates unexpected similarity of the evolved rules and comparable classification accuracy performance of both approaches.
Recent evidence suggests that nanoparticles affect cell membrane stability and subsequently exert toxic effects. To assess these interactions, research is often conducted on lipid vesicles as ...substitutes for cells. We present a methodology that enables observing thousands of lipid vesicles and analysing their shape transformations with the use of computerised image processing and data analysis. Our aim was to test whether this approach is appropriate for assessing effects of nanoparticles (C^sub 60^ and CoFe^sub 2^O^sub 4^) on POPC lipid vesicles. In the presented experiments, we show that nanoparticles provoked bursting of vesicles as well as changes in their size and morphology. The novelty of our approach lies in the possibility to investigate a large population of vesicles and generate statistically relevant results. Our data demonstrates that nanoparticles affected lipid membranes and may have a potential to affect cell membranes as well. PUBLICATION ABSTRACT
Conducting research on lipid vesicles is very convenient, since they provide a stable and controllable environment for in vitro observations. Their resemblance to biological cell membranes allows ...biologists to assess hazardous potential of nanoparticles by exposing the vesicles instead of live organisms. When considering behavior of vesicles during incubation with nanoparticles, majority of existing research focus on observing single vesicles only. Our approach provides an ability to observe thousands of lipid vesicles for more representative behavior estimation. We developed an efficient algorithm to transform video sequences acquired with video microscopy into quantitative data. This includes steps required to filter noise, use multiple frames for more precise content presentation, detection of regions of interest, and segmentation of circular and non-primitively shaped vesicles. Presented work is a crucial step towards the creation of an automated computer analysis for lipid vesicles behavior assessment.
Novel properties of nanoparticles have numerous potential technological applications but at the same time they underlie new kinds of biological effects. Uniqueness of nanoparticles and nanomaterials ...requires a new experimental methodology. Much evidence suggests that nanoparticles affect cell membrane stability and subsequently exert toxic effects. For this kind of research, lipid vesicles are of high value due to controllability and repeatability of experimental conditions. The aim of work presented here was to develop a computer aided analysis of lipid vesicles shape transformations. We studied a population of palmitoyloleoylphosphatidylcholine (POPC) lipid vesicles after exposure to nanoparticles (C 60 ) or a reference chemical (ZnCl 2 ). With the use of computer image analysis methods, we detected differences in size distributions of vesicles in different exposure groups. Though, at the present state, we are not able to precisely identify effects of nanoparticles on shape transformations of vesicles, those incubated with nanoparticles were in average larger than those in other groups. This population based approach holds many promises for future investigation of nanoparticles-lipid vesicles, or even nanoparticles-biological membranes interactions. However, in order to get reliable results, numerous images have to be analyzed which requires improved and highly automated image segmentation and analyses methods.
Zika Virus Associated with Microcephaly Mlakar, Jernej; Korva, Misa; Tul, Nataša ...
The New England journal of medicine,
2016-Mar-10, Volume:
374, Issue:
10
Journal Article
Peer reviewed
Open access
A widespread epidemic of Zika virus (ZIKV) infection was reported in 2015 in South and Central America and the Caribbean. A major concern associated with this infection is the apparent increased ...incidence of microcephaly in fetuses born to mothers infected with ZIKV. In this report, we describe the case of an expectant mother who had a febrile illness with rash at the end of the first trimester of pregnancy while she was living in Brazil. Ultrasonography performed at 29 weeks of gestation revealed microcephaly with calcifications in the fetal brain and placenta. After the mother requested termination of the pregnancy, a fetal autopsy was performed. Micrencephaly (an abnormally small brain) was observed, with almost complete agyria, hydrocephalus, and multifocal dystrophic calcifications in the cortex and subcortical white matter, with associated cortical displacement and mild focal inflammation. ZIKV was found in the fetal brain tissue on reverse-transcriptase-polymerase-chain-reaction (RT-PCR) assay, with consistent findings on electron microscopy. The complete genome of ZIKV was recovered from the fetal brain.
Cloud cover is a major limiting factor in exploiting time-series data acquired by optical spaceborne remote sensing sensors. Multiple methods have been developed to address the problem of cloud ...detection in satellite imagery and a number of cloud masking algorithms have been developed for optical sensors but very few studies have carried out quantitative intercomparison of state-of-the-art methods in this domain. This paper summarizes results of the first Cloud Masking Intercomparison eXercise (CMIX) conducted within the Committee Earth Observation Satellites (CEOS) Working Group on Calibration & Validation (WGCV). CEOS is the forum for space agency coordination and cooperation on Earth observations, with activities organized under working groups. CMIX, as one such activity, is an international collaborative effort aimed at intercomparing cloud detection algorithms for moderate-spatial resolution (10–30 m) spaceborne optical sensors. The focus of CMIX is on open and free imagery acquired by the Landsat 8 (NASA/USGS) and Sentinel-2 (ESA) missions. Ten algorithms developed by nine teams from fourteen different organizations representing universities, research centers and industry, as well as space agencies (CNES, ESA, DLR, and NASA), are evaluated within the CMIX. Those algorithms vary in their approach and concepts utilized which were based on various spectral properties, spatial and temporal features, as well as machine learning methods. Algorithm outputs are evaluated against existing reference cloud mask datasets. Those datasets vary in sampling methods, geographical distribution, sample unit (points, polygons, full image labels), and generation approaches (experts, machine learning, sky images). Overall, the performance of algorithms varied depending on the reference dataset, which can be attributed to differences in how the reference datasets were produced. The algorithms were in good agreement for thick cloud detection, which were opaque and had lower uncertainties in their identification, in contrast to thin/semi-transparent clouds detection. Not only did CMIX allow identification of strengths and weaknesses of existing algorithms and potential areas of improvements, but also the problems associated with the existing reference datasets. The paper concludes with recommendations on generating new reference datasets, metrics, and an analysis framework to be further exploited and additional input datasets to be considered by future CMIX activities.
•Ten cloud masking algorithms for Landsat 8 and Sentinel-2 are evaluated.•Algorithm performance varied depending on the reference dataset.•Average overall accuracy for Sentinel-2 was 80.0 ± 5.3% to 89.4 ± 2.4%.•Average overall accuracy for Landsat 8 was 79.8 ± 7.1% to 97.6 ± 0.8%.•Performance of algorithms improved when thin/semi-transparent clouds not considered.
PDF
