39,647 research outputs found
Partition of Two Interacting Electrons by a Potential Barrier
No full text7 pages (including references)+ 7 pages (supplemental material), more
discussions includedScattering or tunneling of an electron at a potential barrier is a fundamental quantum effect. Electron-electron interactions often affect the scattering, and understanding of the interaction effect is crucial in detection of various phenomena of electron transport and their application to electron quantum optics. We theoretically study the partition and collision of two interacting hot electrons at a potential barrier. We predict their kinetic energy change by their Coulomb interaction during the scattering delay time inside the barrier. The energy change results in characteristic deviation of the partition probabilities from the noninteracting case. The derivation includes nonmonotonic dependence of the probabilities on the barrier height, which qualitatively agrees with recent experiments, and reduction of the fermionic antibunching.This work is supported by Korea NRF via the SRC Center for Quantum Coherence in Condensed Matter (Grant No. 2016R1A5A1008184). S. R. acknowledges partial support from the María de Maeztu Program for Units of Excellence No. MDM2017-0711 funded by MCIN/AEI/10.13039/501100011033.Peer reviewe
A simple disc wind model for broad absorption line quasars
No full textApproximately 20 per cent of quasi-stellar objects (QSOs) exhibit broad, blue-shifted absorption lines in their ultraviolet spectra. Such features provide clear evidence for significant outflows from these systems, most likely in the form of accretion disc winds. These winds may represent the ‘quasar’ mode of feedback that is often invoked in galaxy formation/evolution models, and they are also key to unification scenarios for active galactic nuclei (AGN) and QSOs. To test these ideas, we construct a simple benchmark model of an equatorial, biconical accretion disc wind in a QSO and use a Monte Carlo ionization/radiative transfer code to calculate the ultraviolet spectra as a function of viewing angle. We find that for plausible outflow parameters, sightlines looking directly into the wind cone do produce broad, blue-shifted absorption features in the transitions typically seen in broad absorption line (BAL) QSOs. However, our benchmark model is intrinsically X-ray weak in order to prevent overionization of the outflow, and the wind does not yet produce collisionally excited line emission at the level observed in non-BAL QSOs. As a first step towards addressing these shortcomings, we discuss the sensitivity of our results to changes in the assumed X-ray luminosity and mass-loss rate, Ṁwind. In the context of our adopted geometry, Ṁwind ∼ Ṁacc is required in order to produce significant BAL features. The kinetic luminosity and momentum carried by such outflows would be sufficient to provide significant feedback
Partition of Two Interacting Electrons by a Potential Barrier
No full textScattering or tunneling of an electron at a potential barrier is a fundamental quantum effect. Electron-electron interactions often affect the scattering, and understanding of the interaction effect is crucial in detection of various phenomena of electron transport and their application to electron quantum optics. We theoretically study the partition and collision of two interacting hot electrons at a potential barrier in the quantum Hall regime. We predict their kinetic energy change by their Coulomb interaction during the scattering delay time inside the barrier. The energy change results in characteristic deviation of the partition probabilities from the noninteracting case. The derivation includes nonmonotonic dependence of the probabilities on the barrier height, which agrees with recent experiments, and reduction of the fermionic antibunching.This work is supported by Korea NRF via the SRC Center for Quantum Coherence in Condensed Matter (Grant No. 2016R1A5A1008184). S. R. acknowledges partial support from the María de Maeztu Program for Units of Excellence No. MDM2017-0711 funded by MCIN/AEI/10.13039/501100011033.N
Coulomb blockade and Kondo effect in a quantum hall antidot
No full textWe propose a general capacitive model for an antidot, which has two localized edge states with different spins in the quantum Hall regime. The capacitive coupling of localized excess charges, which are generated around the antidot due to magnetic flux quantization, and their effective spin fluctuation can result in Coulomb blockade, h/(2e) Aharonov-Bohm oscillations, and the Kondo effect. The resultant conductance is in qualitative agreement with recent experimental data.H. S. S. and M. K. thank C. J. B. Ford and H. Schomerus
for helpful discussions. The discussions with K. Kikoin,
K. Kang, and T. S. Kim are acknowledged.We were supported
by SKORE-A(HY and MSC), eSSC (MSC), and
QSRC at Dongguk University (SREY)
The sim gene of Escherichia coli phage P1: nucleotide sequence and purification of the processed protein
No full textMaillou J, Dreiseikelmann B. The sim gene of Escherichia coli phage P1: nucleotide sequence and purification of the processed protein. Virology. 1990;175(2):500-507.The sim gene of bacteriophage P1 causes exclusion of a superinfecting P1 phage. We determined the nucleotide sequence of a 1.9-kb DNA fragment that, in plasmids, causes Sim phenotype. There are two open reading frames within this region for proteins of 82 and 259 amino acids. A 1.3-kb fragment containing the larger open reading frame was inserted into an expression vector. Induced cells carrying the hybrid plasmid, termed pBD5, were not infected by phage P1 and produced a 24-kDa protein and, to a smaller extent, a 25-kDa protein. The 24-kDa protein was purified. Comparison of its amino-terminal amino acid sequence with the nucleotide sequence indicated that it is processed from a precursor protein by removal of a hydrophobic leader peptide of 20 amino acids. In vivo processing depends on secA gene function and is necessary for Sim interference with P1 infection. The data are discussed with respect to the function of the sim gene in superinfection exclusion
Retention of data in heat-damaged SIM cards and potential recovery methods
No full textExamination of various SIM cards and smart card devices indicates that data may be retained in SIM card memory structures even after heating to temperatures up to 450oC, which the National Institute of Standards and Technology (NIST) has determined to be approximately the maximum average sustained temperature at desk height in a house fire. However, in many cases, and certainly for temperatures greater than 450oC, the SIM card chip has suffered structural or mechanical damage that renders simple probing or rewiring ineffective. Nevertheless, this has not necessarily affected the data, which is stored as charge in floating gates, and alternative methods for directly accessing the stored charge may be applicable
Shot Noise in Ballistic Quantum Dots with a Mixed Classical Phase Space.
No full textWe investigate shot noise for quantum dots whose classical phase space consists of both regular and chaotic regions. The noise is systematically suppressed below the universal value of fully chaotic systems, by an amount which varies with the positions of the leads. We analyze the dynamical origin of this effect by a novel way to incorporate diffractive impurity scattering. The dependence of the shot noise on the scattering rate shows that the suppression arises due to the deterministic nature of transport through regular regions and along short chaotic trajectories. Shot noise can be used to probe phase-space structures of quantum dots with generic classical dynamics
Search for exotic decays of the Higgs boson into b and missing transverse momentum in pp collisions at = 13 TeV with the ATLAS detector
No full textA bstract A search for the exotic decay of the Higgs boson ( H ) into a b b ¯ resonance plus missing transverse momentum is described. The search is performed with the ATLAS detector at the Large Hadron Collider using 139 fb − 1 of pp collisions at s = 13 TeV. The search targets events from ZH production in an NMSSM scenario where H → χ ~ 2 0 χ ~ 1 0 , with χ ~ 2 0 → a χ ~ 1 0 , where a is a light pseudoscalar Higgs boson and χ ~ 1 , 2 0 are the two lightest neutralinos. The decay of the a boson into a pair of b -quarks results in a peak in the dijet invariant mass distribution. The final-state signature consists of two leptons, two or more jets, at least one of which is identified as originating from a b -quark, and missing transverse momentum. Observations are consistent with Standard Model expectations and upper limits are set on the product of cross section times branching ratio for a three-dimensional scan of the masses of the χ ~ 2 0 , χ ~ 1 0 and a boson
Functional characterization of the ribosome biogenesis factors PES, BOP1, and WDR12 (PeBoW), and mechanisms of defective cell growth and proliferation caused by PeBoW deficiency in Arabidopsis
No full textThe nucleolar protein pescadillo (PES) controls biogenesis of the 60S ribosomal subunit through functional interactions with Block of Proliferation 1 (BOP1) and WD Repeat Domain 12 (WDR12) in plants. In this study, we determined protein characteristics and in planta functions of BOP1 and WDR12, and characterized defects in plant cell growth and proliferation caused by a deficiency of PeBoW (PES-BOP1-WDR12) proteins. Dexamethasone-inducible RNAi of BOP1 and WDR12 caused developmental arrest and premature senescence in Arabidopsis, similar to the phenotype of PES RNAi. Both the N-terminal domain and WD40 repeats of BOP1 and WDR12 were critical for specific associations with 60S/80S ribosomes. In response to nucleolar stress or DNA damage, PeBoW proteins moved from the nucleolus to the nucleoplasm. Kinematic analyses of leaf growth revealed that depletion of PeBoW proteins led to dramatically suppressed cell proliferation, cell expansion, and epidermal pavement cell differentiation. A deficiency in PeBoW proteins resulted in reduced cyclin-dependent kinase Type A activity, causing reduced phosphorylation of histone H1 and retinoblastoma-related (RBR) protein. PeBoW silencing caused rapid transcriptional modulation of cell-cycle genes, including reduction of E2Fa and Cyclin D family genes, and induction of several KRP genes, accompanied by down-regulation of auxin-related genes and up-regulation of jasmonic acid-related genes. Taken together, these results suggest that the PeBoW proteins involved in ribosome biogenesis play a critical role in plant cell growth and survival, and their depletion leads to inhibition of cell-cycle progression, possibly modulated by phytohormone signaling. © 2016 The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology6
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