399 research outputs found

    Numerical simulations of cyclic voltammetry for lithium-ion intercalation in nanosized systems:finiteness of diffusion versus electrode kinetics

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    The voltammetric behavior of Li(+)intercalation/deintercalation in/from LiMn(2)O(4)thin films and single particles is simulated, supporting very recent experimental results. Experiments and calculations both show that particle size and geometry are crucial for the electrochemical response. A remarkable outcome of this research is that higher potential sweep rates, of the order of several millivolts per second, may be used to characterize nanoparticles by voltammetry sweeps, as compared with macroscopic systems. This is in line with previous conclusions drawn for related single particle systems using kinetic Monte Carlo simulations. The impact of electrode kinetics and finite space diffusion on the reversibility of the process and the finiteness of the diffusion in ion Li / LiMn2O4(de)intercalation is also discussed in terms of preexisting modeling

    Evidence for a mixed mass composition at the `ankle' in the cosmic-ray spectrum

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    We report a first measurement for ultra-high energy cosmic rays of the correlation between the depth of shower maximum and the signal in the water Cherenkov stations of air-showers registered simultaneously by the fluorescence and the surface detectors of the Pierre Auger Observatory. Such a correlation measurement is a unique feature of a hybrid air-shower observatory with sensitivity to both the electromagnetic and muonic components. It allows an accurate determination of the spread of primary masses in the cosmic-ray flux. Up till now, constraints on the spread of primary masses have been dominated by systematic uncertainties. The present correlation measurement is not affected by systematics in the measurement of the depth of shower maximum or the signal in the water Cherenkov stations. The analysis relies on general characteristics of air showers and is thus robust also with respect to uncertainties in hadronic event generators. The observed correlation in the energy range around the `ankle' at lg⁡(E/eV)=18.5−19.0\lg(E/{\rm eV})=18.5-19.0 differs significantly from expectations for pure primary cosmic-ray compositions. A light composition made up of proton and helium only is equally inconsistent with observations. The data are explained well by a mixed composition including nuclei with mass A>4A > 4. Scenarios such as the proton dip model, with almost pure compositions, are thus disfavoured as the sole explanation of the ultrahigh-energy cosmic-ray flux at Earth.Comment: Published version. Added journal reference and DOI. Added Report Numbe

    Integrative phylogenetic, phylogeographic and morphological characterisation of the Unio crassus species complex reveals cryptic diversity with important conservation implications

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    The global decline of freshwater mussels and their crucial ecological services highlight the need to understand their phylogeny, phylogeography and patterns of genetic diversity to guide conservation efforts. Such knowledge is urgently needed for Unio crassus, a highly imperilled species originally widespread throughout Europe and southwest Asia. Recent studies have resurrected several species from synonymy based on mitochondrial data, revealing U. crassus to be a complex of cryptic species. To address long-standing taxonomic uncertainties hindering effective conservation, we integrate morphometric, phylogenetic, and phylogeographic analyses to examine species diversity within the U. crassus complex across its entire range. Phylogenetic analyses were performed using cytochrome c oxidase subunit I (815 specimens from 182 populations) and, for selected specimens, whole mitogenome sequences and Anchored Hybrid Enrichment (AHE) data on ∌ 600 nuclear loci. Mito-nuclear discordance was detected, consistent with mitochondrial DNA gene flow between some species during the Pliocene and Pleistocene. Fossil-calibrated phylogenies based on AHE data support a Mediterranean origin for the U. crassus complex in the Early Miocene. The results of our integrative approach support 12 species in the group: the previously recognised Unio bruguierianus, Unio carneus, Unio crassus, Unio damascensis, Unio ionicus, Unio sesirmensis, and Unio tumidiformis, and the reinstatement of five nominal taxa: Unio desectus stat. rev., Unio gontierii stat. rev., Unio mardinensis stat. rev., Unio nanus stat. rev., and Unio vicarius stat. rev. Morphometric analyses of shell contours reveal important morphospace overlaps among these species, highlighting cryptic, but geographically structured, diversity. The distribution, taxonomy, phylogeography, and conservation of each species are succinctly described.We thank Ana-Maria Benedek, Monica SĂźrbu and Jouni Leinikki for their assistance with the fieldwork, and to Jeroen Goud, Sankurie Pye, Fiona Ware, Emily Mitchell, and Aleksandra Skawina for their assistance with the taxonomic investigation. We would also like to thank the editor, Dr. Guillermo OrtĂ­, and two anonymous reviewers for their time and effort in reviewing our manuscript and for their insightful comments and valuable improvements to our work. This publication is based upon work from COST Action CA18239: CONFREMU - Conservation of freshwater mussels: a pan-European approach, supported by COST (European Cooperation in Science and Technology), including STSMs, the interaction of the authors and the writing of the paper. This work was supported by the project ConBiomics: The Missing Approach for the Conservation of Freshwater Bivalves Project No. POCI-01-0145-FEDER-030286, co-financed by FEDER through POCI and by FCT - Fundaç˜ao para a Ciˆencia e a Tecnologia, through national funds. Strategic funding UIDB/04423/2020 and UIDP/04423/2020 was provided by FCT. FCT also supported DVG (2020.03848.CEECIND), EF (CEECINST/00027/ 2021/CP2789/CT0003) and MLL (2020.03608.CEECIND). INB, AVK and IVV were supported by the Russian Science Foundation under grants (19-14-00066-P), (21-17-00126) and (21-74-10130) respectively. BVB acknowledges the bioinformatics platform of UMR 8198 for the computing resources to perform time-calibrated phylogenetic analyses; this platform is in part funded by CPER research project CLIMIBIO through the French Minist`ere de l’Enseignement SupÂŽerieur et de la Recherche, the Agence Nationale de la Recherche, the European Fund for Regional Development (FEDER) and the region Hauts-de-France (HdF). Support to KD came from the Czech Science Foundation (19–05510S). TT and MT were supported by the National Science Fund of Bulgaria under the project ‘Conservation of freshwater mussels on the Balkan Peninsula’ (KP-06-COST-9/20.07.2022). Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the United States Government.info:eu-repo/semantics/publishedVersio

    Influence of birth cohort on age of onset cluster analysis in bipolar I disorder

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    PURPOSE: Two common approaches to identify subgroups of patients with bipolar disorder are clustering methodology (mixture analysis) based on the age of onset, and a birth cohort analysis. This study investigates if a birth cohort effect will influence the results of clustering on the age of onset, using a large, international database. METHODS: The database includes 4037 patients with a diagnosis of bipolar I disorder, previously collected at 36 collection sites in 23 countries. Generalized estimating equations (GEE) were used to adjust the data for country median age, and in some models, birth cohort. Model-based clustering (mixture analysis) was then performed on the age of onset data using the residuals. Clinical variables in subgroups were compared. RESULTS: There was a strong birth cohort effect. Without adjusting for the birth cohort, three subgroups were found by clustering. After adjusting for the birth cohort or when considering only those born after 1959, two subgroups were found. With results of either two or three subgroups, the youngest subgroup was more likely to have a family history of mood disorders and a first episode with depressed polarity. However, without adjusting for birth cohort (three subgroups), family history and polarity of the first episode could not be distinguished between the middle and oldest subgroups. CONCLUSION: These results using international data confirm prior findings using single country data, that there are subgroups of bipolar I disorder based on the age of onset, and that there is a birth cohort effect. Including the birth cohort adjustment altered the number and characteristics of subgroups detected when clustering by age of onset. Further investigation is needed to determine if combining both approaches will identify subgroups that are more useful for research

    Performance of novel VUV-sensitive Silicon Photo-Multipliers for nEXO

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    Liquid xenon time projection chambers are promising detectors to search for neutrinoless double beta decay (0ÎœÎČÎČ\nu \beta \beta), due to their response uniformity, monolithic sensitive volume, scalability to large target masses, and suitability for extremely low background operations. The nEXO collaboration has designed a tonne-scale time projection chamber that aims to search for 0ÎœÎČÎČ\nu \beta \beta of \ce{^{136}Xe} with projected half-life sensitivity of 1.35×10281.35\times 10^{28}~yr. To reach this sensitivity, the design goal for nEXO is ≀\leq1\% energy resolution at the decay QQ-value (2458.07±0.312458.07\pm 0.31~keV). Reaching this resolution requires the efficient collection of both the ionization and scintillation produced in the detector. The nEXO design employs Silicon Photo-Multipliers (SiPMs) to detect the vacuum ultra-violet, 175 nm scintillation light of liquid xenon. This paper reports on the characterization of the newest vacuum ultra-violet sensitive Fondazione Bruno Kessler VUVHD3 SiPMs specifically designed for nEXO, as well as new measurements on new test samples of previously characterised Hamamatsu VUV4 Multi Pixel Photon Counters (MPPCs). Various SiPM and MPPC parameters, such as dark noise, gain, direct crosstalk, correlated avalanches and photon detection efficiency were measured as a function of the applied over voltage and wavelength at liquid xenon temperature (163~K). The results from this study are used to provide updated estimates of the achievable energy resolution at the decay QQ-value for the nEXO design
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