561 research outputs found

    The phylogenetically distinct early human embryo

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    The phylogenetic singularity of the human embryo remains unresolved as cell types of the human blastocyst have resisted classification. Combining clustering of single cellular transcriptomes and dynamically expressed genes we resolve the cell types. This unveils the missing inner cell mass (ICM) and reveals classical step-wise development. Conversely, numerous features render our blastocyst phylogenetically distinct: unlike mice, our epiblast is self-renewing and we have blastocyst non-committed cells (NCCs), part of an apoptosis-mediated quality control/purging process. At the transcriptome-level all primate embryos are distinct as the pluripotent cell types are uniquely fast evolving. A substantial fraction of gene expression gain and loss events between human and new-world monkeys involve endogenous retrovirus H (ERVH). Human pluripotent cells are unique in which (H)ERVH's are active, the extent to which these modulate neighbour gene expression and their ability to suppress mutagenic transposable elements. Current naive cultures are heterogeneous and both developmentally and phylogenetically "confused"

    Simulations of Supernova Remnants in Diffuse Media III. The Population of Buoyant Remnants Above the Milky Way's Disk

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    We model SNRs at a variety of heights above the disk. Our detailed numerical simulations include non-equilibrium ionization and recombination and follow the remnants' evolution until their hot bubbles have cooled. We analytically calculate the bubbles' buoyant acceleration. From the results, we estimate the time and space average O VI, N V, and C IV column densities and emission intensities, 1/4 keV soft X-ray surface brightness, area coverage, and volume occupation of the population of isolated SNRs above the Galaxy's HI layer. Irrespective of assumed supernova explosion energy, ambient nonthermal pressure, or frictional drag coefficient, the predicted O VI column density matches the observed distribution between 130 pc and 2000 pc. The SNRs' O VI intensity is a significant fraction of the average observed intensity. Within the range of uncertainty in the SN rate, such SNRs can explain all of the observed 1/4 keV surface brightness attributed to the extraplanar gas beyond the H I layer in the southern hemisphere (~400 x 10^-6 counts/s/arcmin^2). Thus, extraplanar SNRs could be the most important source of hot gas between the Local Bubble and z ~ 2000 pc in the relatively quiescent southern hemisphere. These results stand whether the remnants are assumed to be buoyant or not. The population of old extraplanar SNRs should cover most of the high latitude sky, but bright young extraplanar SNRs should cover less than 1% of the sky. Perhaps the l=247, b=-64 crescent in the 1/4 keV X-ray maps could be a young remnant.Comment: Accepted by ApJ for publication on February 10, 2006 (Volume 638). 44 pages, including 6 figures, 10 tables (and 1 blank page

    Equilibrium shapes and energies of coherent strained InP islands

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    The equilibrium shapes and energies of coherent strained InP islands grown on GaP have been investigated with a hybrid approach that has been previously applied to InAs islands on GaAs. This combines calculations of the surface energies by density functional theory and the bulk deformation energies by continuum elasticity theory. The calculated equilibrium shapes for different chemical environments exhibit the {101}, {111}, {\=1\=1\=1} facets and a (001) top surface. They compare quite well with recent atomic-force microscopy data. Thus in the InP/GaInP-system a considerable equilibration of the individual islands with respect to their shapes can be achieved. We discuss the implications of our results for the Ostwald ripening of the coherent InP islands. In addition we compare strain fields in uncapped and capped islands.Comment: 10 pages including 6 figures. Submitted to Phys. Rev. B. Related publications can be found at http://www.fhi-berlin.mpg.de/th/paper.htm

    A reporting and analysis framework for structured evaluation of COVID-19 clinical and imaging data

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    The COVID-19 pandemic has worldwide individual and socioeconomic consequences. Chest computed tomography has been found to support diagnostics and disease monitoring. A standardized approach to generate, collect, analyze, and share clinical and imaging information in the highest quality possible is urgently needed. We developed systematic, computer-assisted and context-guided electronic data capture on the FDA-approved mint LesionTM software platform to enable cloud-based data collection and real-time analysis. The acquisition and annotation include radiological findings and radiomics performed directly on primary imaging data together with information from the patient history and clinical data. As proof of concept, anonymized data of 283 patients with either suspected or confirmed SARS-CoV-2 infection from eight European medical centers were aggregated in data analysis dashboards. Aggregated data were compared to key findings of landmark research literature. This concept has been chosen for use in the national COVID-19 response of the radiological departments of all university hospitals in Germany

    Search for a dark vector gauge boson decaying to π+π\pi^+ \pi^- using ηπ+πγ\eta \rightarrow \pi^+\pi^- \gamma decays

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    We report a search for a dark vector gauge boson UU^\prime that couples to quarks in the decay chain D+D0π+,D0KS0η,ηUγD^{*+} \to D^0 \pi^+, D^0 \to K^0_S \eta, \eta \to U^\prime \gamma, Uπ+πU^\prime \to \pi^+ \pi^-. No signal is found and we set a mass-dependent limit on the baryonic fine structure constant of 10310210^{-3} - 10^{-2} in the UU^\prime mass range of 290 to 520 MeV/c2c^2. This analysis is based on a data sample of 976 fb1^{-1} collected by the Belle experiment at the KEKB asymmetric-energy e+ee^+e^- collider.Comment: 6 pages, 4 figure

    Invariant-mass and fractional-energy dependence of inclusive production of di-hadrons in e+ee^+e^- annihilation at s=\sqrt{s}= 10.58 GeV

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    The inclusive cross sections for di-hadrons of charged pions and kaons (e+ehhXe^+e^- \rightarrow hhX) in electron-positron annihilation are reported. They are obtained as a function of the total fractional energy and invariant mass for any di-hadron combination in the same hemisphere as defined by the thrust event-shape variable and its axis. Since same-hemisphere di-hadrons can be assumed to originate predominantly from the same initial parton, di-hadron fragmentation functions are probed. These di-hadron fragmentation functions are needed as an unpolarized baseline in order to quantitatively understand related spin-dependent measurements in other processes and to apply them to the extraction of quark transversity distribution functions in the nucleon. The di-hadron cross sections are obtained from a 655fb1655\,{\rm fb}^{-1} data sample collected at or near the Υ(4S)\Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+ee^+ e^- collider.Comment: 21 pages, 18 figures plus 25 figures in supplemental material, submitted to PR

    Observation of D0ρ0γD^0\to \rho^0\gamma and search for CPCP violation in radiative charm decays

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    We report the first observation of the radiative charm decay D0ρ0γD^0 \to \rho^0 \gamma and the first search for CPCP violation in decays D0ρ0γD^0 \to \rho^0 \gamma, ϕγ\phi\gamma, and K0γ\overline{K}{}^{*0} \gamma, using a data sample of 943 fb1^{-1} collected with the Belle detector at the KEKB asymmetric-energy e+ee^+e^- collider. The branching fraction is measured to be B(D0ρ0γ)=(1.77±0.30±0.07)×105\mathcal{B}(D^0 \to \rho^0 \gamma)=(1.77 \pm 0.30 \pm 0.07) \times 10^{-5}, where the first uncertainty is statistical and the second is systematic. The obtained CPCP asymmetries, ACP(D0ρ0γ)=+0.056±0.152±0.006\mathcal{A}_{CP}(D^0 \to \rho^0 \gamma)=+0.056 \pm 0.152 \pm 0.006, ACP(D0ϕγ)=0.094±0.066±0.001\mathcal{A}_{CP}(D^0 \to \phi \gamma)=-0.094 \pm 0.066 \pm 0.001, and ACP(D0K0γ)=0.003±0.020±0.000\mathcal{A}_{CP}(D^0 \to \overline{K}{}^{*0} \gamma)=-0.003 \pm 0.020 \pm 0.000, are consistent with no CPCP violation. We also present an improved measurement of the branching fractions B(D0ϕγ)=(2.76±0.19±0.10)×105\mathcal{B}(D^0 \to \phi \gamma)=(2.76 \pm 0.19 \pm 0.10) \times 10^{-5} and B(D0K0γ)=(4.66±0.21±0.21)×104\mathcal{B}(D^0 \to \overline{K}{}^{*0} \gamma)=(4.66 \pm 0.21 \pm 0.21) \times 10^{-4}

    Study of Excited Ξc\Xi_c States Decaying into Ξc0\Xi_c^0 and Ξc+\Xi_c^+ Baryons

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    Using a data sample of 980 fb1{\rm fb}^{-1} of e+ee^+e^- annihilation data taken with the Belle detector operating at the KEKB asymmetric-energy e+ee^+e^- collider, we report the results of a study of excited Ξc\Xi_c states that decay, via the emission of photons and/or charged pions, into Ξc0\Xi_c^0 or Ξc+\Xi_c^+ ground state charmed-strange baryons. We present new measurements of the masses of all members of the Ξc\Xi_c^{\prime}, Ξc(2645)\Xi_c(2645), Ξc(2790)\Xi_c(2790), Ξc(2815)\Xi_c(2815), and Ξc(2980)\Xi_c(2980) isodoublets, measurements of the intrinsic widths of those that decay strongly, and evidence of previously unknown transitions.Comment: Submitted to PR

    Search for Λc+ϕpπ0\Lambda_c^+\to\phi p \pi^0 and branching fraction measurement of Λc+Kπ+pπ0\Lambda_c^+\to K^-\pi^+ p \pi^0

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    We have searched for the Cabibbo-suppressed decay Λc+ϕpπ0\Lambda_c^+\to\phi p\pi^0 in e+ee^+e^- collisions using a data sample corresponding to an integrated luminosity of 915 fb1\rm fb^{-1}. The data were collected by the Belle experiment at the KEKB e+ee^+e^- asymmetric-energy collider running at or near the Υ(4S)\Upsilon(4S) and Υ(5S)\Upsilon(5S) resonances. No significant signal is observed, and we set an upper limit on the branching fraction of B(Λc+ϕpπ0)<15.3×105\mathcal{B}(\Lambda_c^+\to \phi p\pi^0) <15.3\times10^{-5} at 90% confidence level. The contribution for nonresonant Λc+K+Kpπ0\Lambda_c^+\to K^+K^- p\pi^0 decays is found to be consistent with zero and the corresponding upper limit on its branching fraction is set to be B(Λc+K+Kpπ0)NR<6.3×105\mathcal{B}(\Lambda_c^+\to K^+K^-p\pi^0)_{\rm NR} <6.3\times10^{-5} at 90% confidence level. We also measure the branching fraction for the Cabibbo-favored decay Λc+Kπ+pπ0\Lambda_c^+\to K^-\pi^+p\pi^0; the result is B(Λc+Kπ+pπ0)=(4.42±0.05(stat.)±0.12(syst.)±0.16(BNorm))%\mathcal{B}(\Lambda_c^+\to K^-\pi^+p\pi^0)= (4.42\pm0.05\, (\rm stat.) \pm 0.12\, (\rm syst.) \pm 0.16\, (\mathcal{B}_{\rm Norm}))\%, which is the most precise measurement to date. Finally, we have searched for an intermediate hidden-strangeness pentaquark decay Ps+ϕpP^+_s\to\phi p. We see no evidence for this intermediate decay and set an upper limit on the product branching fraction of B(Λc+Ps+π0)×B(Ps+ϕp)<8.3×105{\cal B}(\Lambda_c^+\to P^+_s \pi^0)\times {\cal B}(P^+_s\to\phi p) <8.3\times 10^{-5} at 90% confidence level.Comment: 8 pages, 5 figures, 1 table, minor text change in version
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