Accessibility-based reranking in multimedia search engines

Traditional multimedia search engines retrieve results based mostly on the query submitted by the user, or using a log of previous searches to provide personalized results, while not considering the accessibility of the results for users with vision or other types of impairments. In this paper, a novel approach is presented which incorporates the accessibility of images for users with various vision impairments, such as color blindness, cataract and glaucoma, in order to rerank the results of an image search engine. The accessibility of individual images is measured through the use of vision simulation filters. Multi-objective optimization techniques utilizing the image accessibility scores are used to handle users with multiple vision impairments, while the impairment profile of a specific user is used to select one from the Pareto-optimal solutions. The proposed approach has been tested with two image datasets, using both simulated and real impaired users, and the results verify its applicability. Although the proposed method has been used for vision accessibility-based reranking, it can also be extended for other types of personalization context

Distribution of air temperature multifractal characteristics over Greece

In this study, Multifractal Detrended Fluctuation Analysis (MF-DFA) is applied to daily temperature time series (mean, maximum and minimum values) from 22 Greek meteorological stations with the purpose of examining firstly their scaling behavior and then checking if there are any differences in their multifractal characteristics. The results showed that the behavior is the same at almost all stations, i.e., time series are positive long-term correlated and their multifractal structure is insensitive to local fluctuations with large magnitude. Moreover, this study deals with the spatial distribution of the main characteristics of multifractal (singularity) spectrum: the dominant Hurst exponent, the width of the spectrum, the asymmetry and the truncation type of the spectrum. The spatial distributions are discussed in terms of possible effects from various climatic features. In general, local atmospheric circulation and weather conditions are found to affect the shape of the spectrum and the corresponding spatial distributions. Furthermore, the intercorrelation of the main multifractal spectrum parameters resulted in a well-defined group of stations sharing similar multifractal characteristics. The results indicate the usefulness of the non-linear analysis in climate research due to the complex interactions among the natural processes. © 2018 by the authors

Microbial adaptation to high ammonia concentrations during anaerobic digestion of manure-based feedstock: biomethanation and 16S rRNA gene sequencing

BACKGROUND: Microbial consortia resistant to high ammonia concentrations may facilitate biogas production from high ammonia-containing wastes and manures during anaerobic digestion. Microbial communities were gradually enriched via sequential batch cultivations (stepwise exposure) at increasing ammonia concentrations up to the extremely high concentration of 9 g total ammonia nitrogen (TAN) L−1. This study examined the adaptation of anaerobic microbial consortia to high ammonia concentrations by the use of a complex substrate based on manure in order to generate tailor-made inocula for bioaugmentation purposes. RNA analysis was performed to determine the microbial community composition and activity of anaerobic bacteria and methanogens. RESULTS: The enrichment series was successful in terms of methane production at ammonia concentrations as high as 5 g TAN L−1 in comparison with the control concentration of 2 g TAN L−1. Methanosarcina was the core active dominant methanogen genus in all enrichment cultures and its relative activity was sharply increased at 3 g and 9 g TAN L−1. Cellulolytic bacteria activity mostly decreased with ammonia increase. Moreover, syntrophic butyrate and long-chain fatty acid degraders along with hydrogenotrophic methanogens were activated at increased ammonia concentrations. CONCLUSIONS: The results of the study demonstrated an efficient method to enrich ammonia-tolerant microbial consortia for bioaugmentation purposes in biogas reactors with concentrations ≤5 g TAN L−1. RNA analysis revealed high relative abundances of Methanosarcina and hydrogenotrophic methanogens at high concentrations of ammonia. © 2020 Society of Chemical Industry. © 2020 Society of Chemical Industr

Multifractal Detrended Fluctuation Analysis of temperature reanalysis data over Greece

The Multifractal Detrended Fluctuation Analysis (MF-DFA) is used to examine the scaling behavior and the multifractal characteristics of the mean daily temperature time series of the ERA-Interim reanalysis data for a domain centered over Greece. The results showed that the time series from all grid points exhibit the same behavior: they have a positive long-term correlation and their multifractal structure is insensitive to local fluctuations with a large magnitude. Special emphasis was given to the spatial distribution of the main characteristics of the multifractal spectrum: the value of the Hölder exponent, the spectral width, the asymmetry, and the truncation type of the spectra. The most interesting finding is that the spatial distribution of almost all spectral parameters is decisively determined by the land-sea distribution. The results could be useful in climate research for examining the reproducibility of the nonlinear dynamics of reanalysis datasets and model outputs. © 2019 by the authors

Ammonia-induced inhibition of manure-based continuous biomethanation process under different organic loading rates and associated microbial community dynamics

Three Continuously Stirred Tank Reactors (CTSRs) were operating at steady state conditions with Organic Loading Rates (OLR) of 2.09, 3.024 and 4.0 g VS L−1 d−1. Glucose was used as the sole factor for increasing the OLR, linking the increase of the OLR with the C/N ratio increase. The reactors were stressed by increasing the ammonia concentration to 5 g L−1 from 1.862 g L−1. The results showed elevating inhibition of the anaerobic process by increasing the C/N ratio just by increasing the OLR, under the high ammonia concentration. A different response of the bacterial and archaeal community under ammonia stressed conditions was also observed. Under the high ammonia concentration, hydrogen-depended methylotrophic was the dominant methanogenesis route at OLR of 2.09 g VS L−1d−1, while the hydrogenotrophic route was the dominant at the high OLR of 4 g VS L−1d−1, which coincided with high acetate and propionate concentrations. © 2020 Elsevier Lt

The 5′ regulatory region of the human fetal globin genes is a gene conversion hotspot

The human fetal globin genes consist of the first mammalian genomic loci for which gene conversion was reported. To date, 14 gene conversions have been described in the human Gγ- and Aγ-globin genes, the vast majority of which are restricted to the coding sequences. Here, we provide evidence for three new gene conversion events in the 5′ regulatory region of the human fetal globin genes, identified during a large genetic screening effort in adult individuals with high fetal hemoglobin (Hb) levels. The sequence variations, resulting from these conversion events, are transcriptionally silent polymorphisms that do not contribute to increased fetal Hb levels. Our results suggest that the 5′ regulatory region of the human fetal globin genes is a gene conversion hotspot that prevent globin gene promoter sequence diversification, further underlining the need for two functional fetal globin genes in fetal erythropoiesis. Copyright © Informa Healthcare USA, Inc

The 5′ regulatory region of the human fetal globin genes is a gene conversion hotspot

The human fetal globin genes consist of the first mammalian genomic loci for which gene conversion was reported. To date, 14 gene conversions have been described in the human Gγ- and Aγ-globin genes, the vast majority of which are restricted to the coding sequences. Here, we provide evidence for three new gene conversion events in the 5′ regulatory region of the human fetal globin genes, identified during a large genetic screening effort in adult individuals with high fetal hemoglobin (Hb) levels. The sequence variations, resulting from these conversion events, are transcriptionally silent polymorphisms that do not contribute to increased fetal Hb levels. Our results suggest that the 5′ regulatory region of the human fetal globin genes is a gene conversion hotspot that prevent globin gene promoter sequence diversification, further underlining the need for two functional fetal globin genes in fetal erythropoiesis. Copyright © Informa Healthcare USA, Inc

Kinetic and mechanistic studies of the water–gas shift reaction on Pt/TiO2 catalyst

Summarization: A detailed kinetic and mechanistic study of the water–gas shift (WGS) reaction on a 0.5 wt% Pt/TiO2 catalyst has been carried out. The dependence of kinetic reaction rate on the partial pressures of reactants (CO, H2O) and products (H2, CO2), and the concentration and chemical structure of active and inactive reaction intermediates that are found in the “hydrogen-path” and “carbon-path” of the reaction have been investigated in the 200–270 °C range. The most likely mechanistic pathway of the WGS reaction over the present catalytic system is discussed. It has been found that the reaction rate increases with an increase in the concentration of CO or H2O in the feed stream, while it decreases significantly with the addition of H2 in the feed stream. On the contrary, the kinetic reaction rate was found to be practically independent on the concentration of CO2 in the feed stream. The experimental reaction rates that were estimated were fitted to an empirical power-law rate expression from which the kinetic reaction orders with respect to CO, H2O, CO2, and H2 were estimated to be 0.5, 1.0, ∼0.0, and −0.7, respectively. An apparent activation energy of 10.8 kcal/mol was also estimated. The formation of formate and carbonate surface species over the TiO2 support under WGS reaction conditions was proved via SSITKA–DRIFTS experiments. However, these reaction intermediates must be considered as inactive (spectator) species for the steady-state WGS reaction. Additional transient experiments that involved 18O-isotope provided strong support for the red-ox mechanism as the prevailing one on the present Pt/TiO2 catalyst, where labile oxygen and oxygen vacancies of TiO2 near the metal–support interface can participate in the reaction path of the WGS reaction.Presented on: Journal of Catalysi

Large-scale population genetic analysis for hemoglobinopathies reveals different mutation spectra in central Greece compared to the rest of the country

We have undertaken a large population screening study to identify the molecular basis of hemoglobinopathies in the central Greece region. A total of 845 unrelated beta-thalassemia patients and alpha-, beta-, and delta beta-thalassemia carriers have been recruited and screened for mutations in the a- and P-globin gene clusters. The alpha(-MED) deletion and the Turkish inversion/deletion are the most frequent genetic rearrangements leading to alpha- and delta beta-thalassemia respectively, contrary to the situation in the rest of the country, while the beta-101 (C > T) promoter mutation is surprisingly frequent in the central part of Greece. Our data indicate that determination of mutation frequencies in different regions is vital for accurate provision of genetic services and counseling and for precise estimation of genetic diversity