K2-231 b: A sub-Neptune exoplanet transiting a solar twin in Ruprecht 147

We identify a sub-Neptune exoplanet ($R_p = 2.5 \pm 0.2$ R$_\oplus$) transiting a solar twin in the Ruprecht 147 star cluster (3 Gyr, 300 pc, [Fe/H] = +0.1 dex). The ~81 day light curve for EPIC 219800881 (V = 12.71) from K2 Campaign 7 shows six transits with a period of 13.84 days, a depth of ~0.06%, and a duration of ~4 hours. Based on our analysis of high-resolution MIKE spectra, broadband optical and NIR photometry, the cluster parallax and interstellar reddening, and isochrone models from PARSEC, Dartmouth, and MIST, we estimate the following properties for the host star: $M_\star = 1.01 \pm 0.03$ M$_\odot$, $R_\star= 0.95 \pm 0.03$ R$_\odot$, and $T_{\rm eff} = 5695 \pm 50$ K. This star appears to be single, based on our modeling of the photometry, the low radial velocity variability measured over nearly ten years, and Keck/NIRC2 adaptive optics imaging and aperture-masking interferometry. Applying a probabilistic mass-radius relation, we estimate that the mass of this planet is $M_p = 7 +5 -3$ M$_\oplus$, which would cause a RV semi-amplitude of $K = 2 \pm 1$ m s$^{-1}$ that may be measurable with existing precise RV facilities. After statistically validating this planet with BLENDER, we now designate it K2-231 b, making it the second sub-stellar object to be discovered in Ruprecht 147 and the first planet; it joins the small but growing ranks of 23 other planets found in open clusters.Comment: 24 pages, 7 figures, light curve included as separate fil

Entanglement capability of self-inverse Hamiltonian evolution

We determine the entanglement capability of self-inverse Hamiltonian evolution, which reduces to the known result for Ising Hamiltonian, and identify optimal input states for yielding the maximal entanglement rate. We introduce the concept of the operator entanglement rate, and find that the maximal operator entanglement rate gives a lower bound on the entanglement capability of a general Hamiltonian.Comment: 4 pages, no figures. Version 3: small change

A global view of transcriptional regulation by nuclear receptors: gene expression, factor localization, and DNA sequence analysis

Recent genomic analyses of transcription factor binding, histone modification, and gene expression have provided a global view of transcriptional regulation by nuclear receptors (NRs) that complements an existing large body of literature on gene-specific studies. The picture emerging from these genomic studies indicates that NRs bind at promoter-proximal and promoter-distal enhancers in conjunction with other transcription factors (e.g., activator protein-1, Sp1 and FOXA1). This binding promotes the recruitment of coregulators that mediate the posttranslational modification of histones at promoters and enhancers. Ultimately, signaling through liganded NRs stimulates changes in the occupancy of RNA polymerase II (Pol II) or the activation of preloaded Pol II at target promoters. Chromosomal looping and/or Pol II tracking may underlie promoter-enhancer communication. Interestingly, the direct target genes of NR signaling represent a limited subset of all the genes regulated by NR ligands, with the rest being regulated through secondary effects. As suggested by previous gene-specific analyses, NR-mediated outcomes are highly cell type- and promoter-specific, highlighting the complexity of transcriptional regulation by NRs and the value of genomic analyses for identifying commonly shared patterns. Overall, NRs share common themes in their patterns of localization and transcriptional regulation across mammalian genomes. In this review, we provide an overview of recent advances in the understanding of NR-mediated transcription garnered from genomic analyses of gene expression, factor localization, and target DNA sequences

Holographic principle in the BDL brane cosmology

We study the holographic principle in the brane cosmology. Especially we describe how to accommodate the 5D anti de Sitter Schwarzschild (AdSS$_5$) black hole in the Binetruy-Deffayet-Langlois (BDL) approach of brane cosmology. It is easy to make a connection between a mass $M$ of the AdSS$_5$ black hole and a conformal field theory (CFT)-radiation dominated universe on the brane in the moving domain wall approach. But this is not established in the BDL approach. In this case we use two parameters $C_1, C_2$ in the Friedmann equation. These arise from integration and are really related to the choice of initial bulk matter. If one chooses a bulk energy density $\rho_B$ to account for a mass $M$ of the AdSS$_5$ black hole and the static fifth dimension, a CFT-radiation term with $\rho_{CFT} \sim M/a^{4}$ comes out from the bulk matter without introducing a localized matter distribution on the brane. This means that the holographic principle can be established in the BDL brane cosmology.Comment: 9 pages, a version to appear in PR

Genome-wide analysis reveals PADI4 cooperates with Elk-1 to activate c-Fos expression in breast cancer cells.

Peptidylarginine deiminase IV (PADI4) catalyzes the conversion of positively charged arginine and methylarginine residues to neutrally charged citrulline, and this activity has been linked to the repression of a limited number of target genes. To broaden our knowledge of the regulatory potential of PADI4, we utilized chromatin immunoprecipitation coupled with promoter tiling array (ChIP-chip) analysis to more comprehensively investigate the range of PADI4 target genes across the genome in MCF-7 breast cancer cells. Results showed that PADI4 is enriched in gene promoter regions near transcription start sites (TSSs); and, surprisingly, this pattern of binding is primarily associated with actively transcribed genes. Computational analysis found potential binding sites for Elk-1, a member of the ETS oncogene family, to be highly enriched around PADI4 binding sites; and coimmunoprecipitation analysis then confirmed that Elk-1 physically associates with PADI4. To better understand how PADI4 may facilitate gene transactivation, we then show that PADI4 interacts with Elk-1 at the c-Fos promoter and that, following Epidermal Growth Factor (EGF) stimulation, PADI4 catalytic activity facilitates Elk-1 phosphorylation, histone H4 acetylation, and c-Fos transcriptional activation. These results define a novel role for PADI4 as a transcription factor co-activator

Cosmology of intersecting brane world models in Gauss-Bonnet gravity

We study the cosmological properties of a codimension two brane world that sits at the intersection between two four branes, in the framework of six dimensional Einstein-Gauss-Bonnet gravity. Due to contributions of the Gauss-Bonnet terms, the junction conditions require the presence of localized energy density on the codimension two defect. The induced metric on this surface assumes a FRW form, with a scale factor associated to the position of the brane in the background; we can embed on the codimension two defect the preferred form of energy density. We present the cosmological evolution equations for the three brane, showing that, for the case of pure AdS$_6$ backgrounds, they acquire the same form of the ones for the Randall-Sundrum II model. When the background is different from pure AdS$_6$, the cosmological behavior is potentially modified in respect to the typical one of codimension one brane worlds. We discuss, in a particular model embedded in an AdS$_6$ black hole, the conditions one should satisfy in order to obtain standard cosmology at late epochs.Comment: 19 pages, no figures, JHEP style. v2: Typos corrected and references adde

PARP inhibitors and the treatment of breast cancer: beyond BRCA1/2?

Poly(ADP-ribose) polymerase (PARP) inhibitors have been explored as therapeutic agents for the treatment of hereditary breast and ovarian cancers harboring mutations in BRCA1 or BRCA2. In a new study, Inbar-Rozensal and colleagues show that phenanthridine-derived PARP inhibitors promote cell cycle arrest and cell death in breast cancer cells lacking BRCA1 and BRCA2 mutations and prevent the growth of tumors from xenografts of these cells in immunocompromised mice. These results suggest a potential broader utility of PARP-1 inhibitors in the treatment of breast cancer, although further mechanistic studies are needed

No chiral truncation of quantum log gravity?

At the classical level, chiral gravity may be constructed as a consistent truncation of a larger theory called log gravity by requiring that left-moving charges vanish. In turn, log gravity is the limit of topologically massive gravity (TMG) at a special value of the coupling (the chiral point). We study the situation at the level of linearized quantum fields, focussing on a unitary quantization. While the TMG Hilbert space is continuous at the chiral point, the left-moving Virasoro generators become ill-defined and cannot be used to define a chiral truncation. In a sense, the left-moving asymptotic symmetries are spontaneously broken at the chiral point. In contrast, in a non-unitary quantization of TMG, both the Hilbert space and charges are continuous at the chiral point and define a unitary theory of chiral gravity at the linearized level.Comment: 20 pages, no figures, references adde

Self-consistent non-Markovian theory of a quantum state evolution for quantum information processing

It is shown that the operator sum representation for non-Markovian dynamics and the Lindblad master equation in Markovian limit can be derived from a formal solution to quantum Liouville equation for a qubit system in the presence of decoherence processes self-consistently. Our formulation is the first principle theory based on projection-operator formalism to obtain an exact reduced density operator in time-convolutionless form starting from the quantum Liouville equation for a noisy quantum computer. The advantage of our approach is that it is general enough to describe a realistic quantum computer in the presence of decoherence provided details of the Hamiltonians are known.Comment: 5page

Strangeness dynamics in relativistic nucleus-nucleus collision

We investigate hadron production as well as transverse hadron spectra in nucleus-nucleus collisions from 2 $A\cdot$GeV to 21.3 $A\cdot$TeV within two independent transport approaches (UrQMD and HSD) that are based on quark, diquark, string and hadronic degrees of freedom. The comparison to experimental data demonstrates that both approaches agree quite well with each other and with the experimental data on hadron production. The enhancement of pion production in central Au+Au (Pb+Pb) collisions relative to scaled $pp$ collisions (the 'kink') is well described by both approaches without involving any phase transition. However, the maximum in the $K^+/\pi^+$ ratio at 20 to 30 A$\cdot$GeV (the 'horn') is missed by $\sim$ 40%. A comparison to the transverse mass spectra from $pp$ and C+C (or Si+Si) reactions shows the reliability of the transport models for light systems. For central Au+Au (Pb+Pb) collisions at bombarding energies above $\sim$ 5 A$\cdot$GeV, however, the measured $K^{\pm}$ $m_{T}$-spectra have a larger inverse slope parameter than expected from the calculations. The approximately constant slope of $K^\pm$ spectra at SPS (the 'step') is not reproduced either. Thus the pressure generated by hadronic interactions in the transport models above $\sim$ 5 A$\cdot$GeV is lower than observed in the experimental data. This finding suggests that the additional pressure - as expected from lattice QCD calculations at finite quark chemical potential and temperature - might be generated by strong interactions in the early pre-hadronic/partonic phase of central Au+Au (Pb+Pb) collisions.Comment: 10 pages, 5 figures, Invited talk presented by H. Stocker at ERICE-2003 (Sep. 2003, Erice, Italy), to be published in Prog. Part. Nucl. Phys. 52 (2004