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Search for vector-like leptons coupling to first- and second-generation Standard Model leptons in pp collisions at s = 13 TeV with the ATLAS detector
No full textAbstract A search for pair production of vector-like leptons coupling to first- and second-generation Standard Model leptons is presented. The search is based on a dataset of proton-proton collisions at s = 13 TeV recorded with the ATLAS detector during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of 140 fb−1. Events are categorised depending on the flavour and multiplicity of leptons (electrons or muons), as well as on the scores of a deep neural network targeting particular signal topologies according to the decay modes of the vector-like leptons. In each of the signal regions, the scalar sum of the transverse momentum of the leptons and the missing transverse momentum is analysed. The main background processes are estimated using dedicated control regions in a simultaneous fit with the signal regions to data. No significant excess above the Standard Model background expectation is observed and limits are set at 95% confidence level on the production cross-sections of vector-like electrons and muons as a function of the vector-like lepton mass, separately for SU(2) doublet and singlet scenarios. The resulting mass lower limits are 1220 GeV (1270 GeV) and 320 GeV (400 GeV) for vector-like electrons (muons) in the doublet and singlet scenarios, respectively
Characterization of aquatic clade 2 and 3 Campylobacter coli isolates from Slovenia reveals admixture with other Campylobacter species
No full textAbstract Campylobacter coli, a significant foodborne pathogen, has undergone extensive genetic exchange with its close relative, Campylobacter jejuni, leading to the emergence of three distinct clades. While clade 1 strains are commonly isolated from clinical and agricultural sources, clades 2 and 3 are primarily found in aquatic environments. This study aimed to enhance our understanding of C. coli clade 2 and 3 isolates through genomic and phenotypic characterization. A total of 48 surface water samples were collected from 19 different water bodies throughout Slovenia, and eleven Campylobacter isolates initially identified as C. coli from clades 2 and 3 were cultured. Whole genome sequencing was then performed on these isolates. Phylogenetic analysis was conducted using core genome multilocus sequence typing (cgMLST) and k-mer analysis. Phenotypic characterization included growth analysis, autoagglutination, biofilm formation, motility, antimicrobial susceptibility, water survival, and metabolic profiling. Genomic analysis revealed significant admixture with other Campylobacter species in the clade 2 and 3 isolates. One isolate was found to represent a new species related to C. coli. Besides C. jejuni and C. lari, this novel species appears to have contributed to introgression in the C. coli clades 2 and 3 isolates. Phenotypic characterization demonstrated diverse growth patterns, motility, autoagglutination abilities, and biofilm formation among the isolates. This study provides new insights into the genetic diversity and phenotypic characteristics of aquatic C. coli clade 2 and 3 isolates from Slovenia. The observed admixture with other Campylobacter species highlights the complex evolutionary history of these environmental strains and underscores the importance of continued surveillance and characterization of Campylobacter isolates from diverse ecological niches
Rosacea as a Neurocutaneous Disorder: In Vivo Corneal Confocal Microscopy Reveals Neurologic Alterations
No full texthttp://dx.doi.org/10.13039/501100004543 China Scholarship Counci
Discovery of the world's largest cliff-top boulder: Initial insights and numerical simulation of its transport on a 30–40 m high cliff on Tongatapu (Tonga)
No full texthttp://dx.doi.org/10.13039/501100014334 JICA Ogata Sadako Research Institute for Peace and Developmenthttp://dx.doi.org/10.13039/501100001037 Australia and Pacific Science Foundationhttp://dx.doi.org/10.13039/501100001691 Japan Society for the Promotion of Scienc
Topographic Effect Creates Non‐climatic Variations in Ice‐Core Based Temperature Records of the Last Millennium in Dronning Maud Land, Antarctica
No full textAbstract Past temperature reconstructions from polar ice sheets are commonly based on stable water isotope records in ice‐cores. However, despite major efforts in the understanding of the ice‐core signal formation, the temperature reconstructions of the last millennium in Antarctica remain uncertain. Here, using a 100 km scale representative surface water isotope dataset, we show that the spatial variability of local surface topography and accumulation rate anomalies influences the isotopic composition of the upper‐meter snowpack. The magnitude of this non‐temperature effect on water isotopes is comparable to the changes observed over the last millennium. We demonstrate that these spatial anomalies are advected into the deeper firn and ice column, and can explain the diverging millennial water isotope trends observed in two ice‐cores near the EPICA Dronning Maud Land drilling site. Furthermore, we provide an estimation of areas where this topographic effect could impact temperature reconstructions over the last millenia.Plain Language Summary Stable water isotopes in ice cores are widely used as proxies for past temperatures. However, these records can be affected by multiple processes and their reliability is unclear, particularly for centennial to millennial time scales in Antarctica. We demonstrate that in low‐accumulation rate regions, local topography induces spatial isotope variability, which ice flow then translates into temporal anomalies in ice‐cores. This mechanism creating non‐temperature related water isotope variations on time‐scales from centuries to millennia might be omnipresent within the continent, potentially affecting numerous ice‐cores. We provide an initial assessment of areas potentially affected by this process, aiming to guide future coring and facilitate the careful interpretation of existing records.Key Points Variations in local topography are linked with anomalies in the isotopic composition of surface snow and in accumulation rates Windward slopes exhibit depleted isotopic values and increased accumulation, while leeward slopes show the opposite pattern This induces millennial scale non‐climatic variations in ice‐cores explaining differing isotopic histories in the nearby cores B31 and B32Abstract Past temperature reconstructions from polar ice sheets are commonly based on stable water isotope records in ice‐cores. However, despite major efforts in the understanding of the ice‐core signal formation, the temperature reconstructions of the last millennium in Antarctica remain uncertain. Here, using a 100 km scale representative surface water isotope dataset, we show that the spatial variability of local surface topography and accumulation rate anomalies influences the isotopic composition of the upper‐meter snowpack. The magnitude of this non‐temperature effect on water isotopes is comparable to the changes observed over the last millennium. We demonstrate that these spatial anomalies are advected into the deeper firn and ice column, and can explain the diverging millennial water isotope trends observed in two ice‐cores near the EPICA Dronning Maud Land drilling site. Furthermore, we provide an estimation of areas where this topographic effect could impact temperature reconstructions over the last millenia.Plain Language Summary Stable water isotopes in ice cores are widely used as proxies for past temperatures. However, these records can be affected by multiple processes and their reliability is unclear, particularly for centennial to millennial time scales in Antarctica. We demonstrate that in low‐accumulation rate regions, local topography induces spatial isotope variability, which ice flow then translates into temporal anomalies in ice‐cores. This mechanism creating non‐temperature related water isotope variations on time‐scales from centuries to millennia might be omnipresent within the continent, potentially affecting numerous ice‐cores. We provide an initial assessment of areas potentially affected by this process, aiming to guide future coring and facilitate the careful interpretation of existing records.Key Points Variations in local topography are linked with anomalies in the isotopic composition of surface snow and in accumulation rates Windward slopes exhibit depleted isotopic values and increased accumulation, while leeward slopes show the opposite pattern This induces millennial scale non‐climatic variations in ice‐cores explaining differing isotopic histories in the nearby cores B31 and B32Abstract Past temperature reconstructions from polar ice sheets are commonly based on stable water isotope records in ice‐cores. However, despite major efforts in the understanding of the ice‐core signal formation, the temperature reconstructions of the last millennium in Antarctica remain uncertain. Here, using a 100 km scale representative surface water isotope dataset, we show that the spatial variability of local surface topography and accumulation rate anomalies influences the isotopic composition of the upper‐meter snowpack. The magnitude of this non‐temperature effect on water isotopes is comparable to the changes observed over the last millennium. We demonstrate that these spatial anomalies are advected into the deeper firn and ice column, and can explain the diverging millennial water isotope trends observed in two ice‐cores near the EPICA Dronning Maud Land drilling site. Furthermore, we provide an estimation of areas where this topographic effect could impact temperature reconstructions over the last millenia.Plain Language Summary Stable water isotopes in ice cores are widely used as proxies for past temperatures. However, these records can be affected by multiple processes and their reliability is unclear, particularly for centennial to millennial time scales in Antarctica. We demonstrate that in low‐accumulation rate regions, local topography induces spatial isotope variability, which ice flow then translates into temporal anomalies in ice‐cores. This mechanism creating non‐temperature related water isotope variations on time‐scales from centuries to millennia might be omnipresent within the continent, potentially affecting numerous ice‐cores. We provide an initial assessment of areas potentially affected by this process, aiming to guide future coring and facilitate the careful interpretation of existing records.Key Points Variations in local topography are linked with anomalies in the isotopic composition of surface snow and in accumulation rates Windward slopes exhibit depleted isotopic values and increased accumulation, while leeward slopes show the opposite pattern This induces millennial scale non‐climatic variations in ice‐cores explaining differing isotopic histories in the nearby cores B31 and B32Horizon 2020 Framework Programme https://doi.org/10.13039/10001066
Degradable film mulching increases soil carbon sequestration in major Chinese dryland agroecosystems
No full textSensitive particle shape dependence of growth-induced mesoscale nematic structure
No full textSubtle changes in particle shape can drastically alter the size distribution of growth-induced microdomains. This can be traced back to different stability properties and breakup dynamics.Directed growth, anisotropic cell shapes, and confinement drive self-organization in multicellular systems. We investigate the influence of particle shape on the distribution and dynamics of nematic microdomains in a minimal in silico model of proliferating, sterically interacting particles, akin to colonies of rod-shaped bacteria. By introducing continuously tuneable tip variations around a common rod shape with spherical caps, we find that subtle changes significantly impact the emergent dynamics, leading to distinct patterns of microdomain formation and stability. Our analysis reveals separate effects of particle shape and aspect ratio, as well as a transition from exponential to scale-free size distributions, which we recapitulate using an effective master equation model. This allows us to relate differences in microdomain size distributions to different physical mechanisms of microdomain breakup. Our results thereby contribute to the characterization of the effective dynamics in growing aggregates at large and intermediate length scales and the microscopic properties that control it. This could be relevant both for biological self-organization and design strategies for future artificial systems.Subtle changes in particle shape can drastically alter the size distribution of growth-induced microdomains. This can be traced back to different stability properties and breakup dynamics.Directed growth, anisotropic cell shapes, and confinement drive self-organization in multicellular systems. We investigate the influence of particle shape on the distribution and dynamics of nematic microdomains in a minimal in silico model of proliferating, sterically interacting particles, akin to colonies of rod-shaped bacteria. By introducing continuously tuneable tip variations around a common rod shape with spherical caps, we find that subtle changes significantly impact the emergent dynamics, leading to distinct patterns of microdomain formation and stability. Our analysis reveals separate effects of particle shape and aspect ratio, as well as a transition from exponential to scale-free size distributions, which we recapitulate using an effective master equation model. This allows us to relate differences in microdomain size distributions to different physical mechanisms of microdomain breakup. Our results thereby contribute to the characterization of the effective dynamics in growing aggregates at large and intermediate length scales and the microscopic properties that control it. This could be relevant both for biological self-organization and design strategies for future artificial systems.Max-Planck-Gesellschaft https://doi.org/10.13039/50110000418
Ionization memory of plasma emitters in a solar prominence
No full textAims. In the low-collisional, partially ionized plasma (PIP) of solar prominences, uncharged emitters might show different signatures of magnetic line broadening than charged emitters. We investigate if the widths of weak metal emissions in prominences exceed the thermal line broadening by a different amount for charged and for uncharged emitters. Methods. We simultaneously observe five optically thin, weak metal lines in the brightness center of a quiescent prominence and compare their observed widths with the thermal broadening. Results. The inferred nonthermal broadening of the metal lines does not indicate systematic differences between the uncharged Mg b 2 and Na D 1 and the charged Fe II emitters, only Sr II is broader. Conclusions. The additional line broadening of charged emitters can reasonably be attributed to magnetic forces. That of uncharged emitters can then come from their temporary state as ions before recombination. Magnetically induced velocities will be retained some time after recombination. Modelling PIPs then requires consideration of a memory of previous ionization states
Effective polarization in potassium channel simulations: Ion conductance, occupancy, voltage response, and selectivity
No full textPotassium (K + ) channels are widely distributed in many types of organisms. They combine high efficiency (~100 pS) and K + /Na + selectivity by a conserved selectivity filter (SF). Molecular Dynamics (MD) simulations can provide detailed, atomistic mechanisms of this sophisticated ion permeation. However, currently there are clear inconsistencies between computational predictions and experimental results. First, the ion occupancy of the SF in simulations is lower than expected (~2.5 in MD compared to ~4 in X-ray crystallography). Second, in many reported MD simulations of K + channels, K + conductance is typically an order of magnitude lower than experimental values. This discrepancy is in part because the force fields used in MD simulations of potassium channels do not account for polarization. One of the proposed solutions is the Electronic Continuum Correction (ECC), a force field modification that scales down formal charges, to introduce the polarization in a mean-field way. When the ECC is used in conjunction with the Charmm36m force field, the simulated K + conductance increases 13-fold. Following the analysis of ion occupancy states using Hamiltonian Replica Exchange simulations, we propose a parameter set for Amber14sb, that also leads to a similar increase in conductance. These two force fields are then used to compute the full current–voltage (I-V) curves from MD simulations, approaching quantitative agreement with experiments at all voltages. In general, the ECC-enabled simulations are in excellent agreement with experiment, in terms of ion occupancy, conductance, current–voltage response, and K + /Na + selectivity.Max Planck SocietyIPF | Leibniz-Gemeinschaft 501100001664Deutsche Forschungsgemeinschaft 50110000165