213 research outputs found

    The broad Fe K line profile in NGC 4151

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    We present an analysis of the Fe K line profile of NGC 4151 by using long ASCA observation data obtained in May 1995. The unprecedented good data quality, which is much better in the energy band around 6.4 keV than that of the famous 4.2-day ASCA observation of MCG -6-30-15 in July 1994, offers a unique opportunity to study the details of Fe K line profile. Apart from those characteristics already noticed in earlier ASCA observations on this object (Yaqoob et al. 1995): a broad and skewed profile, with a strong peak at about 6.4 keV and a large red wing extending to ∼\sim4 - 5 keV, which is remarkably similar to that of MCG -6-30-15, we also find a weak blue wing extending to about 8 keV, thanks to the good quality of the data. When fitted by a relativistic accretion disk line plus a narrow core at 6.4 keV, the data constrain the accretion disk to be nearly face-on, contrary to the edge-on geometry inferred from optical and UV observations. However, the extended blue wing can not be well fitted even after we include corresponding Fe Kβ\beta components. Ni Kα\alpha line emission by an amount of 12% of Fe Kα\alpha is statistically required. An alternative explanation is a model consisting of a narrow core and two disk lines with inclinations of 58o^{\rm o} and 0o^{\rm o}, respectively. We suppose that the component with inclination of 58o^{\rm o} was observed directly, consistent with its edge-on geometry, and the component with inclination of 0o^{\rm o} was scattered into our line of sight by a Compton mirror, which might be the cool accretion disk corona proposed by Poutanen et al. (1996).Comment: 15 pages, including 2 figures, aasms4.sty. To appear in ApJL 52

    Quantum Spectra of Hydrogen Atoms in Various Magnetic Fields with the Closed Orbit Theory

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    The quantum spectra of hydrogen atoms in various magnetic fields have been calculated with the closed orbit theory. The magnitude of the magnetic field decreases from 5.96 T to 0.56T with a step of 0.6T. We demonstrate schematically that the closed orbits disappear with the decrease of the magnitude of the magnetic field when the corresponding finite resolution of experiment is fixed. This may give us a good way to control the shape and the number of the closed orbits in the system, and thus to control where a peak should exist in the Fourier transformation of the quantum spectra.Comment: 4 page

    Signal pathways underlying homocysteine-induced production of MCP-1 and IL-8 in cultured human whole blood

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    Aim : To elucidate the mechanisms underlying homocysteine (Hcy)-induced chemokine production. Methods : Human whole blood was pretreated with inhibitors of calmodulin (CaM), protein kinase C (PKC), protein tyrosine kinase (PTK), mitogen-activated protein kinase (MAPK), and NF-ΚB and activators of PPARΓ for 60 min followed by incubation with Hcy 100 Μmol/L for 32 h. The levels of mitogen chemokine protein (MCP)-1 and interleukin-8 (IL-8) were determined by enzyme-linked immunosorbant assay (ELISA). Results : Inhibitors of PKC (calphostin C, 50-500 nmol/L and RO-31-8220, 10–100 nmol/L), CaM (W7, 28–280 Μmol/L), ERK1/2 MAPK (PD 98059, 2–20 Μmol/L), p38 MAPK (SB 203580, 0.6–6 Μmol/L), JNK MAPK (curcumin, 2–10 Μmol/L), and NF-ΚB (PDTC, 10-100 nmol/L) markedly reduced Hcy 100 Μmol/L-induced production of MCP-1 and IL-8 in human cultured whole blood, but the inhibitors of PTK (genistein, 2.6–26 Μmol/L and tyrphostin, 0.5-5 Μmol/L) had no obvious effect on MCP-1 and IL-8 production. PPARΓ activators (ciglitazone 30 Μmol/L and troglitazone 10 Μmol/L) depressed the Hcy-induced MCP-1 production but not IL-8 production in the cultured whole blood. Conclusion : Hcy-induced MCP-1 and IL-8 production is mediated by activated signaling pathways such as PKC, CaM, MAPK, and NF-ΚB. Our results not only provide clues for the signal transduction pathways mediating Hcy-induced chemokine production, but also offer a plausible explanation for a pathogenic role of hyperhomocysteinemia in these diseases.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75644/1/j.1745-7254.2005.00005.x.pd

    Psoriasis Regression Analysis of MHC Loci Identifies Shared Genetic Variants with Vitiligo

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    Psoriasis is a common inflammatory skin disease with genetic components of both immune system and the epidermis. PSOR1 locus (6q21) has been strongly associated with psoriasis; however, it is difficult to identify additional independent association due to strong linkage disequilibrium in the MHC region. We performed stepwise regression analyses of more than 3,000 SNPs in the MHC region genotyped using Human 610-Quad (Illumina) in 1,139 cases with psoriasis and 1,132 controls of Han Chinese population to search for additional independent association. With four regression models obtained, two SNPs rs9468925 in HLA-C/HLA-B and rs2858881 in HLA-DQA2 were repeatedly selected in all models, suggesting that multiple loci outside PSOR1 locus were associated with psoriasis. More importantly we find that rs9468925 in HLA-C/HLA-B is associated with both psoriasis and vitiligo, providing first important evidence that two major skin diseases share a common genetic locus in the MHC, and a basis for elucidating the molecular mechanism of skin disorders

    RANKL Is a Downstream Mediator for Insulin-Induced Osteoblastic Differentiation of Vascular Smooth Muscle Cells

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    Several reports have shown that circulating insulin level is positively correlated with arterial calcification; however, the relationship between insulin and arterial calcification remains controversial and the mechanism involved is still unclear. We used calcifying vascular smooth muscle cells (CVSMCs), a specific subpopulation of vascular smooth muscle cells that could spontaneously express osteoblastic phenotype genes and form calcification nodules, to investigate the effect of insulin on osteoblastic differentiation of CVSMCs and the cell signals involved. Our experiments demonstrated that insulin could promote alkaline phosphatase (ALP) activity, osteocalcin expression and the formation of mineralized nodules in CVSMCs. Suppression of receptor activator of nuclear factor κB ligand (RANKL) with small interfering RNA (siRNA) abolished the insulin-induced ALP activity. Insulin induced the activation of extracellular signal-regulated kinase (ERK)1/2, mitogen-activated protein kinase (MAPK) and RAC-alpha serine/threonine-protein kinase (Akt). Furthermore, pretreatment of human osteoblasts with the ERK1/2 inhibitor PD98059, but not the phosphoinositide 3-kinase (PI3K) inhibitor, LY294002, or the Akt inhibitor, 1L-6-hydroxymethyl-chiro-inositol 2-(R)-2-O-methyl-3-O-octadecylcarbonate (HIMO), abolished the insulin-induced RANKL secretion and blocked the promoting effect of insulin on ALP activities of CVSMCs. Recombinant RANKL protein recovered the ALP activities decreased by RANKL siRNA in insulin-stimulated CVSMCs. These data demonstrated that insulin could promote osteoblastic differentiation of CVSMCs by increased RANKL expression through ERK1/2 activation, but not PI3K/Akt activation

    Production of doubly-charged Δ\Delta baryon in e+e−e^{+}e^{-} annihilation at energies from 2.3094 to 2.6464 GeV

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    The processes e+e−→Δ++Δˉ−−e^{+}e^{-} \to \Delta^{++}\bar{\Delta}^{--} and e+e−→Δ++pˉπ−+c.c.e^{+}e^{-}\to \Delta^{++} \bar{p} \pi^{-} + c.c. are studied for the first time with 179 pb−1179~{\rm pb}^{-1} of e+e−e^{+}e^{-} annihilation data collected with the BESIII detector at center-of-mass energies from 2.30942.3094 GeV to 2.64642.6464 GeV. No significant signal for the e+e−→Δ++Δˉ−−e^{+}e^{-}\to \Delta^{++}\bar{\Delta}^{--} process is observed and the upper limit of the Born cross section is estimated at each energy point. For the process e+e−→Δ++pˉπ−+c.c.e^{+}e^{-} \to \Delta^{++} \bar{p} \pi^{-} + c.c., a significant signal is observed at center-of-mass energies near 2.6454 GeV and the corresponding Born cross section is reported.Comment: 10 pages, 4 figure

    Observation of Ξ−\Xi^{-} Hyperon Transverse Polarization in ψ(3686)→Ξ−Ξˉ+\psi(3686)\rightarrow\Xi^{-}\bar\Xi^{+}

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    Using a sample of (448.1 ± 2.9)(448.1~\pm~2.9) ×106\times 10^{6} ψ(3686)\psi(3686) decays collected with the BESIII detector at BEPCII, we report an observation of Ξ−\Xi^{-} transverse polarization with a significance of 7.3σ7.3 \sigma in the decay ψ(3686)→Ξ−Ξˉ+\psi(3686)\rightarrow\Xi^{-}\bar\Xi^{+} (Ξ−→π−Λ\Xi^{-}\rightarrow\pi^{-}\Lambda, Ξˉ+→π+Λˉ\bar\Xi^{+}\rightarrow\pi^{+}\bar\Lambda, Λ→pπ−\Lambda\to p\pi^{-}, Λˉ→pˉπ+\bar\Lambda\to\bar{p}\pi^{+}). The relative phase of the electric and magnetic form factors is determined to be ΔΦ=(0.667±0.111±0.058)\Delta\Phi = (0.667 \pm 0.111 \pm 0.058) rad. This is the first measurement of the relative phase for a ψ(3686)\psi(3686) decay into a pair of Ξ−Ξˉ+\Xi^{-}\bar\Xi^{+} hyperons. The Ξ−\Xi^{-} decay parameters (αΞ−\alpha_{\Xi^{-}}, ϕΞ−\phi_{\Xi^-}) and their conjugates (αΞˉ+\alpha_{\bar\Xi^{+}}, ϕΞˉ+\phi_{\bar{\Xi}^{+}}), the angular-distribution parameter αψ\alpha_{\psi}, and the strong-phase difference δp−δs\delta_{p}-\delta_{s} for Λ\Lambda-π−\pi^- scattering are measured to be consistent with previous BESIII results.Comment: 8 pages, 3 figures, consistent with paper published in Phys. Rev. D (Letter) 106, L091101 (2022

    Search for an axion-like particle in J/ψJ/\psi radiative decays

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    We search for an axion-like particle (ALP) aa through the process ψ(3686)→π+π−J/ψ\psi(3686)\rightarrow\pi^+\pi^-J/\psi, J/ψ→γaJ/\psi\rightarrow\gamma a, a→γγa\rightarrow\gamma\gamma in a data sample with (2708.1±14.5)×106(2708.1\pm14.5)\times10^6 ψ(3686)\psi(3686) events collected by the BESIII detector. No significant ALP signal is observed over the expected background, and the upper limits on the branching fraction of the decay J/ψ→γaJ/\psi\rightarrow\gamma a and the ALP-photon coupling constant gaγγg_{a\gamma\gamma} are set at the 95\% confidence level in the mass range of 0.165\leq m_a\leq2.84\,\mbox{GeV}/c^2. The limits on B(J/ψ→γa)\mathcal{B}(J/\psi\rightarrow\gamma a) range from 8.3×10−88.3\times10^{-8} to 1.8×10−61.8\times10^{-6} over the search region, and the constraints on the ALP-photon coupling are the most stringent to date for 0.165\leq m_a\leq1.468\,\mbox{GeV}/c^2.Comment: 10 pages, 5 figure

    Measurements of the electric and magnetic form factors of the neutron for time-like momentum transfer

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    We present the first measurements of the electric and magnetic form factors of the neutron in the time-like (positive q2q^2) region as function of four-momentum transfer. We explored the differential cross sections of the reaction e+e−→nˉne^+e^- \rightarrow \bar{n}n with data collected with the BESIII detector at the BEPCII accelerator, corresponding to an integrated luminosity of 354.6 pb−1^{-1} in total at twelve center-of-mass energies between s=2.0−2.95\sqrt{s} = 2.0 - 2.95 GeV. A relative uncertainty of 18% and 12% for the electric and magnetic form factors, respectively, is achieved at s=2.3935\sqrt{s} = 2.3935 GeV. Our results are comparable in accuracy to those from electron scattering in the comparable space-like (negative q2q^2) region of four-momentum transfer. The electromagnetic form factor ratio Rem≡∣GE∣/∣GM∣R_{\rm em}\equiv |G_E|/|G_M| is within the uncertainties close to unity. We compare our result on ∣GE∣|G_E| and ∣GM∣|G_M| to recent model predictions, and the measurements in the space-like region to test the analyticity of electromagnetic form factors.Comment: main paper: 9 pages, 6 figures, 3 tables; supplement: 9 pages, 28 table

    Measurements of the branching fractions of the inclusive decays D0(D+)→π+π+π−X

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    Using eþe− annihilation data corresponding to an integrated luminosity of 2.93 fb−1 taken at a center-of mass energy of 3.773 GeV with the BESIII detector, we report the first measurements of the branching fractions of the inclusive decays D0 → πþπþπ−X and Dþ → πþπþπ−X, where pions from K0 S decays have been excluded from the πþπþπ− system and X denotes any possible particle combination. The branching fractions of D0ðDþÞ → πþπþπ−X are determined to be BðD0 → πþπþπ−XÞ¼ð17.60 0.11 0.22Þ% and BðDþ → πþπþπ−XÞ¼ð15.25 0.09 0.18Þ%, where the first uncertainties are statistical and the second systematic
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