60 research outputs found
Phylogeography and cryptic species structure of a locally adapted parasite in New Zealand
The phylogeographic patterns of many taxa on New Zealand's South Island are characterized by disjunct distributions that have been attributed to Pleistocene climatic cycles
and the formation of the Southern Alps. Pleistocene glaciation has been implicated in
shaping the contemporary genetic differentiation between populations of the aquatic
snail Potamopyrgus antipodarum. We investigated whether similar phylogeographic
patterns exist for the snail's locally adapted trematode parasite, Atriophallophorus
winterbourni. We found evidence for a barrier to gene-flow in sympatry between
cryptic, but ecologically divergent species. When focusing on the most common of
these species, disjunct geographic distributions are found for mitochondrial lineages
that diverged during the Pleistocene. The boundary between these distributions is
found in the central part of the South Island and is reinforced by low cross-alpine
migration. Further support for a vicariant origin of the phylogeographic pattern was
found when assessing nuclear multilocus SNP data. Nuclear and mitochondrial population differentiation was concordant in pattern, except for populations in a potential
secondary contact zone. Additionally, we found larger than expected differentiation
between nuclear- and mitochondrial-based empirical Bayes F>sub>ST estimates (global FST:
0.02 vs. 0.39 for nuclear and mitochondrial data, respectively). Population subdivision
is theoretically expected to be stronger for mitochondrial genomes due to a smaller
effective population size, but the strong difference here, together with mitonuclear
discordance in a putative contact zone, is potentially indicative of divergent gene flow
of nuclear and mitochondrial genomes
A study of Hate Speech in Social Media during the COVID-19 outbreak
In pandemic situations, hate speech propagates in social media, new forms of stigmatization arise and new groups are targeted with this kind of speech.
In this short article, we present work in progress on the study of hate speech in Spanish tweets related to newspaper articles about the COVID-19 pandemic.
We cover two main aspects: The construction of a new corpus annotated for hate speech in Spanish tweets, and the analysis of the collected data in order to answer questions from the social field, aided by modern computational tools.
Definitions and progress are presented in both aspects. For the corpus, we introduce the data collection process, the annotation schema and criteria, and the data statement. For the analysis, we present our goals and its associated questions. We also describe the definition and training of a hate speech classifier, and present preliminary results using it.Fil: Cotik, Viviana. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil: Debandi, Natalia. Universidad Nacional de Río Negro; Argentina.Fil: Luque, Franco. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación; Argentina.Fil: Luque, Franco. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Miguel, Paula. Universidad de Buenos Aires; Argentina.Fil: Moro, Agustín. Universidad de Buenos Aires; Argentina.Fil: Moro, Agustín. Universidad Nacional del Centro; Argentina.Fil: Pérez, Juan Manuel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil: Serrati, Pablo. Universidad de Buenos Aires; Argentina.Fil: Zajac, Joaquín. Universidad de Buenos Aires; Argentina.Fil: Zayat, Demián. Universidad de Buenos Aires; Argentina
Loss of genetic diversity and increased embryonic mortality in non-native lizard populations
Many populations are small and isolated with limited genetic variation and high risk
of mating with close relatives. Inbreeding depression is suspected to contribute to extinction of wild populations, but the historical and demographic factors that contribute to reduced population viability are often difficult to tease apart. Replicated introduction events in non-native species can offer insights into this problem because they allow us to study how genetic variation and inbreeding depression are affected by demographic events (e.g. bottlenecks), genetic admixture and the extent and duration of isolation. Using detailed knowledge about the introduction history of 21 nonnative populations of the wall lizard Podarcis muralis in England, we show greater loss of genetic diversity (estimated from microsatellite loci) in older populations and in populations from native regions of high diversity. Loss of genetic diversity was accompanied by higher embryonic mortality in non-native populations, suggesting that introduced populations are sufficiently inbred to jeopardize long-term viability. However, there was no statistical correlation between population-level genetic diversity and average embryonic mortality. Similarly, at the individual level, there was no correlation between female heterozygosity and clutch size, infertility or hatching success, or between embryo heterozygosity and mortality. We discuss these results in the context of human-mediated introductions and how the history of introductions can play a fundamental role in influencing individual and population fitness in non-native species
Assessing the impact of contextual information in hate speech detection
In recent years, hate speech has gained great relevance in social networks
and other virtual media because of its intensity and its relationship with
violent acts against members of protected groups. Due to the great amount of
content generated by users, great effort has been made in the research and
development of automatic tools to aid the analysis and moderation of this
speech, at least in its most threatening forms. One of the limitations of
current approaches to automatic hate speech detection is the lack of context.
Most studies and resources are performed on data without context; that is,
isolated messages without any type of conversational context or the topic being
discussed. This restricts the available information to define if a post on a
social network is hateful or not. In this work, we provide a novel corpus for
contextualized hate speech detection based on user responses to news posts from
media outlets on Twitter. This corpus was collected in the Rioplatense
dialectal variety of Spanish and focuses on hate speech associated with the
COVID-19 pandemic. Classification experiments using state-of-the-art techniques
show evidence that adding contextual information improves hate speech detection
performance for two proposed tasks (binary and multi-label prediction). We make
our code, models, and corpus available for further research
Intervertebral disc microbiome in Modic changes: Lack of result replication underscores the need for a consensus in low-biomass microbiome analysis
INTRODUCTION
The emerging field of the disc microbiome challenges traditional views of disc sterility, which opens new avenues for novel clinical insights. However, the lack of methodological consensus in disc microbiome studies introduces discrepancies. The aims of this study were to (1) compare the disc microbiome of non-Modic (nonMC), Modic type 1 change (MC1), and MC2 discs to findings from prior disc microbiome studies, and (2) investigate if discrepancies to prior studies can be explained with bioinformatic variations.
METHODS
Sequencing of 16S rRNA in 70 discs (24 nonMC, 25 MC1, and 21 MC2) for microbiome profiling. The experimental setup included buffer contamination controls and was performed under aseptic conditions. Methodology and results were contrasted with previous disc microbiome studies. Critical bioinformatic steps that were different in our best-practice approach and previous disc microbiome studies (taxonomic lineage assignment, prevalence cut-off) were varied and their effect on results were compared.
RESULTS
There was limited overlap of results with a previous study on MC disc microbiome. No bacterial genera were shared using the same bioinformatic parameters. Taxonomic lineage assignment using "amplicon sequencing variants" was more sensitive and detected 48 genera compared to 22 with "operational taxonomic units" (previous study). Increasing filter cut-off from 4% to 50% (previous study) reduced genera from 48 to 4 genera. Despite these differences, both studies observed dysbiosis with an increased abundance of gram-negative bacteria in MC discs as well as a lower beta-diversity. Cutibacterium was persistently detected in all groups independent of the bioinformatic approach, emphasizing its prevalence.
CONCLUSION
There is dysbiosis in MC discs. Bioinformatic parameters impact results yet cannot explain the different findings from this and a previous study. Therefore, discrepancies are likely caused by different sample preparations or true biologic differences. Harmonized protocols are required to advance understanding of the disc microbiome and its clinical implications
Probing the Roughness of Porphyrin Thin Films with X-ray Photoelectron Spectroscopy
Thin-film growth of molecular systems is of interest for many applications, such as for instance organic electronics. In this study, we demonstrate how X-ray photoelectron spectroscopy (XPS) can be used to study the growth behavior of such molecular systems. In XPS, coverages are often calculated assuming a uniform thickness across a surface. This results in an error for rough films, and the magnitude of this error depends on the kinetic energy of the photoelectrons analyzed. We have used this kinetic-energy dependency to estimate the roughnesses of thin porphyrin films grown on rutile TiO2(110). We used two different molecules: cobalt (II) monocarboxyphenyl-10,15,20-triphenylporphyrin (CoMCTPP), with carboxylic-acid anchor groups, and cobalt (II) tetraphenylporphyrin (CoTPP), without anchor groups. We find CoMCTPP to grow as rough films at room temperature across the studied coverage range, whereas for CoTPP the first two layers remain smooth and even; depositing additional CoTPP results in rough films. Although, XPS is not a common technique for measuring roughness, it is fast and provides information of both roughness and thickness in one measurement.Fil: Kataev, Elmar. Universitat Erlangen-Nuremberg; AlemaniaFil: Wechsler, Daniel. Universitat Erlangen-Nuremberg; AlemaniaFil: Williams, Federico José. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Inorgánica, Analítica y Química Física; ArgentinaFil: Köbl, Julia. Universitat Erlangen-Nuremberg; AlemaniaFil: Tsud, Natalia. Karlova Univerzita (cuni); República ChecaFil: Franchi, Stefano. Istituto di Struttura della Materia; Italia. Consiglio Nazionale delle Ricerche; ItaliaFil: Steinruck, Hans Peter. Universitat Erlangen-Nuremberg; AlemaniaFil: Lytken, Ole. Universitat Erlangen-Nuremberg; Alemani
Reactivity tests for supplementary cementitious materials: RILEM TC 267-TRM phase 1
A primary aim of RILEM TC 267-TRM: “Tests for Reactivity of Supplementary Cementitious Materials (SCMs)” is to compare and evaluate the performance of conventional and novel SCM reactivity test methods across a wide range of SCMs. To this purpose, a round robin campaign was organized to investigate 10 different tests for reactivity and 11 SCMs covering the main classes of materials in use, such as granulated blast furnace slag, fly ash, natural pozzolan and calcined clays. The methods were evaluated based on the correlation to the 28 days relative compressive strength of standard mortar bars containing 30% of SCM as cement replacement and the interlaboratory reproducibility of the test results. It was found that only a few test methods showed acceptable correlation to the 28 days relative strength over the whole range of SCMs. The methods that showed the best reproducibility and gave good correlations used the R3 model system of the SCM and Ca(OH)2, supplemented with alkali sulfate/carbonate. The use of this simplified model system isolates the reaction of the SCM and the reactivity can be easily quantified from the heat release or bound water content. Later age (90 days) strength results also correlated well with the results of the IS 1727 (Indian standard) reactivity test, an accelerated strength test using an SCM/Ca(OH)2-based model system. The current standardized tests did not show acceptable correlations across all SCMs, although they performed better when latently hydraulic materials (blast furnace slag) were excluded. However, the Frattini test, Chapelle and modified Chapelle test showed poor interlaboratory reproducibility, demonstrating experimental difficulties. The TC 267-TRM will pursue the development of test protocols based on the R3 model systems. Acceleration and improvement of the reproducibility of the IS 1727 test will be attempted as well
(Photo)physical properties of new molecular glasses end-capped with thiophene rings composed of diimide and imine units
New symmetrical arylene bisimide derivatives formed by using electron-donating-electron-accepting systems were synthesized. They consist of a phthalic diimide or naphthalenediimide core and imine linkages and are end-capped with thiophene, bithiophene, and (ethylenedioxy)thiophene units. Moreover, polymers were obtained from a new diamine, N,N′-bis(5- aminonaphthalenyl)naphthalene-1,4,5,8-dicarboximide and 2,5- thiophenedicarboxaldehyde or 2,2′-bithiophene-5,5′-dicarboxaldehyde. The prepared azomethine diimides exhibited glass-forming properties. The obtained compounds emitted blue light with the emission maximum at 470 nm. The value of the absorption coefficient was determined as a function of the photon energy using spectroscopic ellipsometry. All compounds are electrochemically active and undergo reversible electrochemical reduction and irreversible oxidation processes as was found in cyclic voltammetry and differential pulse voltammetry (DPV) studies. They exhibited a low electrochemically (DPV) calculated energy band gap (Eg) from 1.14 to 1.70 eV. The highest occupied molecular orbital and lowest unoccupied molecular orbital levels and Eg were additionally calculated theoretically by density functional theory at the B3LYP/6-31G(d,p) level. The photovoltaic properties of two model compounds as the active layer in organic solar cells in the configuration indium tin oxide/poly(3,4-(ethylenedioxy)thiophene):poly(styrenesulfonate)/active layer/Al under an illumination of 1.3 mW/cm2 were studied. The device comprising poly(3-hexylthiophene) with the compound end-capped with bithiophene rings showed the highest value of Voc (above 1 V). The conversion efficiency of the fabricated solar cell was in the range of 0.69-0.90%
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