1,041 research outputs found

    A low-density hot Jupiter in a near-aligned, 4.5-day orbit around a VV = 10.8, F5V star

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    We report the independent discovery and characterisation of a hot Jupiter in a 4.5-d, transiting orbit around the star TYC 7282-1298-1 (VV = 10.8, F5V). The planet has been pursued by the NGTS team as NGTS-2b and by ourselves as WASP-179b. We characterised the system using a combination of photometry from WASP-South and TRAPPIST-South, and spectra from CORALIE (around the orbit) and HARPS (through the transit). We find the planet's orbit to be nearly aligned with its star's spin. From a detection of the Rossiter-McLaughlin effect, we measure a projected stellar obliquity of λ=−19±6∘\lambda = -19 \pm 6^\circ. From line-profile tomography of the same spectra, we measure λ=−11±5∘\lambda = -11 \pm 5^\circ. We find the planet to have a low density (MPM_{\rm P} = 0.67 ±\pm 0.09 MJupM_{\rm Jup}, RPR_{\rm P} = 1.54 ±\pm 0.06 RJupR_{\rm Jup}), which, along with its moderately bright host star, makes it a good target for transmission spectroscopy. We find a lower stellar mass (M∗M_* = 1.30±0.071.30 \pm 0.07 M⊙M_\odot) than reported by the NGTS team (M∗M_* = 1.64±0.211.64 \pm 0.21 M⊙M_\odot), though the difference is only 1.51.5 σ\sigma.Comment: Submitted to AJ. 9 pages, 6 figures, 5 table

    WASP-189b: an ultra-hot Jupiter transiting the bright A star HR 5599 in a polar orbit

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    We report the discovery of WASP-189b: an ultra-hot Jupiter in a 2.72-d transiting orbit around the V=6.6V = 6.6 A star WASP-189 (HR 5599). We detected periodic dimmings in the star's lightcurve, first with the WASP-South survey facility then with the TRAPPIST-South telescope. We confirmed that a planet is the cause of those dimmings via line-profile tomography and radial-velocity measurements using the HARPS and CORALIE spectrographs. Those reveal WASP-189b to be an ultra-hot Jupiter (MPM_{\rm P} = 2.13 ±\pm 0.28 MJupM_{\rm Jup}; RPR_{\rm P} = 1.374 ±\pm 0.082 RJupR_{\rm Jup}) in a polar orbit (λ=89.3±1.4∘\lambda = 89.3 \pm 1.4^\circ; Ψ=90.0±5.8∘\Psi = 90.0 \pm 5.8^\circ) around a rapidly rotating A6IV-V star (TeffT_{\rm eff} = 8000 ±\pm 100 K; v∗sin⁡i∗v_* \sin i_* ≈\approx 100 km\, s−1^{-1}). We calculate a predicted equilibrium temperature of TeqlT_{\rm eql} = 2641 ±\pm 34 K, assuming zero albedo and efficient redistribution, which is the third hottest for the known exoplanets. WASP-189 is the brightest known host of a transiting hot Jupiter and the third-brightest known host of any transiting exoplanet. We note that of the eight hot-Jupiter systems with TeffT_{\rm eff} >> 7000 K, seven have strongly misaligned orbits, and two of the three systems with TeffT_{\rm eff} ≥\geq 8000 K have polar orbits (the third is aligned).Comment: Submitted to MNRAS. 10 pages, 9 figures, 3 table

    Haidinger’s brushes elicited at varying degrees of polarization rapidly and easily assesses total macular pigmentation

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    Macular pigments (MPs), by absorbing potentially toxic short-wavelength (400–500 nm) visible light, provide protection against photo-chemical damage thought to be relevant in the pathogenesis of age-related macular degeneration (AMD). A method of screening for low levels of MPs could be part of a prevention strategy for helping people to delay the onset of AMD. We introduce a new method for assessing MP density that takes advantage of the polarization-dependent absorption of blue light by MPs, which results in the entoptic phenomenon called Haidinger’s brushes (HB). Subjects were asked to identify the direction of rotation of HB when presented with a circular stimulus illuminated with an even intensity of polarized white light in which the electric field vector was rotating either clockwise or anti-clockwise. By reducing the degree of polarization of the stimulus light, a threshold for perceiving HB (degree of polarization threshold) was determined and correlated (r2=0.66) to macular pigment optical density assessed using dual-wavelength fundus autofluoresence. The speed and ease of measurement of degree of polarization threshold makes it well suited for large-scale screening of macular pigmentation

    Intimate Partner Violence during Pregnancy: Victim or Perpetrator? Does it make a difference?

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    Objectives: To differentiate between forms of intimate partner violence (IPV)(victim only, perpetrator only, or participating in reciprocal violence) and examine risk profiles and pregnancy outcomes. Design: Prospective Setting: Washington, DC, July 2001 to October 2003 Sample: 1044 high-risk African-American pregnant women who participated in a randomized controlled trial to address IPV, depression, smoking, and environmental tobacco smoke exposure. Methods: Multivariable linear and logistic regression Main outcome measures: Low and very low birth weight, preterm and very preterm birth Results: 5% of women were victims only, 12% were perpetrators only, 27% participated in reciprocal violence, and 55% reported no IPV. Women reporting reciprocal violence in the past year were more likely to drink, use illicit drugs, and experience environmental tobacco smoke exposure and were less likely to be very happy about their pregnancies. Women reporting any type of IPVwere more likely to be depressed than those reporting no IPV. Women experiencing reciprocal violence reported highest levels of depression. Women who were victims of IPV were more likely to give birth prior prematurely and deliver low and very low birth weight infants. Conclusions: We conclude that women were at highest risk for pregnancy risk factors when they participated in reciprocal violence and thus might be at higher risk for long-term consequences, but women who were victims of intimate partner violence were more likely to show proximal negative outcomes like preterm birth and low birth weight. Different types of interventions may be needed for these two forms of intimate partner violence

    Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

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    The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

    Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

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    The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

    Azimuthal anisotropy of charged particles at high transverse momenta in PbPb collisions at sqrt(s[NN]) = 2.76 TeV

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    The azimuthal anisotropy of charged particles in PbPb collisions at nucleon-nucleon center-of-mass energy of 2.76 TeV is measured with the CMS detector at the LHC over an extended transverse momentum (pt) range up to approximately 60 GeV. The data cover both the low-pt region associated with hydrodynamic flow phenomena and the high-pt region where the anisotropies may reflect the path-length dependence of parton energy loss in the created medium. The anisotropy parameter (v2) of the particles is extracted by correlating charged tracks with respect to the event-plane reconstructed by using the energy deposited in forward-angle calorimeters. For the six bins of collision centrality studied, spanning the range of 0-60% most-central events, the observed v2 values are found to first increase with pt, reaching a maximum around pt = 3 GeV, and then to gradually decrease to almost zero, with the decline persisting up to at least pt = 40 GeV over the full centrality range measured.Comment: Replaced with published version. Added journal reference and DO

    Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV

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    A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 inverse femtobarns. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.Comment: Submitted to JHE

    Combined search for the quarks of a sequential fourth generation

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    Results are presented from a search for a fourth generation of quarks produced singly or in pairs in a data set corresponding to an integrated luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in 2011. A novel strategy has been developed for a combined search for quarks of the up and down type in decay channels with at least one isolated muon or electron. Limits on the mass of the fourth-generation quarks and the relevant Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a simple extension of the standard model with a sequential fourth generation of fermions. The existence of mass-degenerate fourth-generation quarks with masses below 685 GeV is excluded at 95% confidence level for minimal off-diagonal mixing between the third- and the fourth-generation quarks. With a mass difference of 25 GeV between the quark masses, the obtained limit on the masses of the fourth-generation quarks shifts by about +/- 20 GeV. These results significantly reduce the allowed parameter space for a fourth generation of fermions.Comment: Replaced with published version. Added journal reference and DO
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