Studying Double Charm Decays of B_{u,d} and B_{s} Mesons in the MSSM with R-parity Violation

Motivated by the possible large direct CP asymmetry of \bar{B}^0_d \to D^+ D^- decay measured by Belle collaboration, we investigate double charm B_{u,d} and B_s decays in the minimal supersymmetric standard model with R-parity violation. We derive the bounds on relevant R-parity violating couplings from the current experimental data, which show quite consistent measurements among relative collaborations. Using the constrained parameter spaces, we explore R-parity violating effects on other observables in these decays, which have not been measured or have not been well measured yet. We find that the R-parity violating effects on the mixing-induced CP asymmetries of \bar{B}^0_d \to D^{(*)+} D^{(*)-} and \bar{B}^0_s \to D^{(*)+}_s D^{(*)-}_s decays could be very large, nevertheless the R-parity violating effects on the direct CP asymmetries could not be large enough to explain the large direct CP violation of \bar{B}^0_d \to D^{+} D^{-} from Belle. Our results could be used to probe R-parity violating effects and will correlate with searches for direct R-parity violating signals in future experiments.Comment: 28 pages and 6 figures, matches published versio

Click-aware purchase prediction with push at the top

Eliciting user preferences from purchase records for performing purchase prediction is challenging because negative feedback is not explicitly observed, and because treating all non-purchased items equally as negative feedback is unrealistic. Therefore, in this study, we present a framework that leverages the past click records of users to compensate for the missing user-item interactions of purchase records, i.e., non-purchased items. We begin by formulating various model assumptions, each one assuming a different order of user preferences among purchased, clicked-but-not-purchased, and non-clicked items, to study the usefulness of leveraging click records. We implement the model assumptions using the Bayesian personalized ranking model, which maximizes the area under the curve for bipartite ranking. However, we argue that using click records for bipartite ranking needs a meticulously designed model because of the relative unreliableness of click records compared with that of purchase records. Therefore, we ultimately propose a novel learning-to-rank method, called P3Stop, for performing purchase prediction. The proposed model is customized to be robust to relatively unreliable click records by particularly focusing on the accuracy of top-ranked items. Experimental results on two real-world e-commerce datasets demonstrate that P3STop considerably outperforms the state-of-the-art implicit-feedback-based recommendation methods, especially for top-ranked items.Comment: For the final published journal version, see https://doi.org/10.1016/j.ins.2020.02.06

Molecular methods for genomic analyses of variant PML-RARA or other RARA-related chromosomal translocations in acute promyelocytic leukemia

TO THE EDITOR: We read an interesting paper by Palta et al. in a recent issue of the Korean Journal of Hematology titled, "ZBTB16-RARA variant of acute promyelocytic leukemia with tuberculosis: a case report and review of literature" [1]. We would like to add some comments to their article and suggest additional molecular methods to confirm variant translocations in acute promyelocytic leukemia (APL)...

Kinetic stabilization of Fe film on (4 by 2)-GaAs(100)

We grow Fe film on (4 by 2)-GaAs(100) at low temperature, (~ 130 K) and study their chemical structure by photoelectron spectroscopy using synchrotron radiation. We observe the effective suppression of As segregation and remarkable reduction of alloy formation near the interface between Fe and substrate. Hence, this should be a way to grow virtually pristine Fe film on GaAs(100). Further, the Fe film is found stable against As segregation even after warmed up to room temperature. There only forms very thin, ~ 8 angstrom thick interface alloy. It is speculated that the interface alloy forms via surface diffusion mediated by interface defects formed during the low temperature growth of the Fe film. Further out-diffusion of both Ga and As are suppressed because it should then proceed via inefficient bulk diffusion.Comment: 4 figure

Ultralow threshold on-chip microcavity nanocrystal quantum dot lasers

Chemically synthesized nanocrystal, CdSe/ZnS (core/shell), quantum dots are coated on the surface of an ultrahigh-Q toroidal microcavity and the lasing is observed at room and liquid nitrogen temperature by pulsed excitation of quantum dots, either through tapered fiber or free space. Use of a tapered fiber coupling substantially lowered the threshold energy when compared with the case of free space excitation. The reason for the threshold reduction is attributed to the efficient delivery of pump pulses to the active gain region of the toroidal microcavity. Further threshold reduction was possible by quantum dot surface-coverage control. By decreasing the quantum dot numbers on the surface of the cavity, the threshold energy is further decreased down to 9.9 fJ

Dimerization-Induced Fermi-Surface Reconstruction in IrTe2

We report a de Haas-van Alphen (dHvA) oscillation study on IrTe2 single crystals showing complex dimer formations. By comparing the angle dependence of dHvA oscillations with band structure calculations, we show distinct Fermi surface reconstruction induced by a 1/5-type and a 1/8-type dimerizations. This verifies that an intriguing quasi-two-dimensional conducting plane across the layers is induced by dimerization in both cases. A phase transition to the 1/8 phase with higher dimer density reveals that local instabilities associated with intra-and interdimer couplings are the main driving force for complex dimer formations in IrTe2.X11149sciescopu