399 research outputs found
Numerical simulations of cyclic voltammetry for lithium-ion intercalation in nanosized systems:finiteness of diffusion versus electrode kinetics
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
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 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 . 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
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Integrative phylogenetic, phylogeographic and morphological characterisation of the Unio crassus species complex reveals cryptic diversity with important conservation implications
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 - FundaçËao
para a CiËencia 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 lâEnseignement 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
(19â05510S). TT and MT were supported by the National Science Fund
of Bulgaria under the project âConservation of freshwater mussels on the
Balkan Peninsulaâ (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
Efeito de compostos fenĂłlicos, carvĂŁo ativado e do meio fĂsico no desenvolvimento de segmento nodal de Cordia verbenacea L.
Influence of birth cohort on age of onset cluster analysis in bipolar I disorder
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
Liquid xenon time projection chambers are promising detectors to search for
neutrinoless double beta decay (0), 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
0 of \ce{^{136}Xe} with projected half-life sensitivity of
~yr. To reach this sensitivity, the design goal for nEXO is
1\% energy resolution at the decay -value (~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 -value for the
nEXO design
Misturas de um solo laterĂtico com cimento e bentonita para uso em cortinas verticais
Densidade de um planossolo sob sistemas de cultivo avaliada por meio da tomografia computadorizada de raios gama
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