965 research outputs found

    The overmassive black hole in NGC 1277: new constraints from molecular gas kinematics

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    We report the detection of CO(1-0) emission from NGC 1277, a lenticular galaxy in the Perseus Cluster. NGC 1277 has previously been proposed to host an overmassive black hole (BH) compared to the galaxy bulge luminosity (mass), based on stellar-kinematic measurements. The CO(1-0) emission, observed with the IRAM Plateau de Bure Interferometer (PdBI) using both, a more compact (2.9-arcsec resolution) and a more extended (1-arcsec resolution) configuration, is likely to originate from the dust lane encompassing the galaxy nucleus at a distance of 0.9 arcsec (~320 pc). The double-horned CO(1-0) profile found at 2.9-arcsec resolution traces 1.5×108 M1.5\times 10^8\ M_\odot of molecular gas, likely orbiting in the dust lane at $\sim 550\ \mathrm{km\ s^{-1}},whichsuggestsatotalenclosedmassof, which suggests a total enclosed mass of \sim 2\times 10^{10}\ M_\odot.At1arcsecresolution,theCO(10)emissionappearsspatiallyresolvedalongthedustlaneineastwestdirection,thoughatalowsignaltonoiseratio.Inagreementwiththepreviousstellarkinematicmeasurements,theCO(10)kinematicsisfoundtobeconsistentwithan. At 1-arcsec resolution, the CO(1-0) emission appears spatially resolved along the dust lane in east-west direction, though at a low signal-to-noise ratio. In agreement with the previous stellar-kinematic measurements, the CO(1-0) kinematics is found to be consistent with an \sim 1.7\times 10^{10}\ M_\odotBHforastellarmasstolightratioof BH for a stellar mass-to-light ratio of M/L_V=6.3,whilealessmassiveBHof, while a less massive BH of \sim 5\times 10^{9}\ M_\odotispossiblewhenassumingalarger is possible when assuming a larger M/L_V=10$. While the molecular gas reservoir may be associated with a low level of star formation activity, the extended 2.6-mm continuum emission is likely to originate from a weak AGN, possibly characterized by an inverted radio-to-millimetre spectral energy distribution. Literature radio and X-ray data indicate that the BH in NGC 1277 is also overmassive with respect to the Fundamental Plane of BH activity.Comment: 15 pages, 13 figures; accepted for publication in MNRAS on 20 January 2016; updated version including minor changes and note added in proo

    Preditores da qualidade de vida e Incapacidade funcional em doentes com lombalgia crónica em tratamento diferenciado

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    A lombalgia constitui uma causa frequente de morbilidade e de incapacidade e é um motivo frequente de procura dos cuidados de saúde. O presente estudo teve por objectivo identificar os preditores da qualidadede vida e da incapacidade funcional em doentes com lombalgia crónica submetidos a tratamento convencional (fisioterapia) e tratamento por acupunctura e, contribuir ainda para um maior conhecimento dos factores psicológicos na lombalgia. Os resultados mostraram que no grupo de acupunctura, os preditores da qualidadede vida foram as habilitações, depressão, ansiedade, satisfação com as despesas, incapacidade funcional e pertencer a uma família extrema, enquanto que no grupo de fisioterapia, os preditores foram a depressão, ansiedade, incapacidade funcional e consequências da doença. Ao nível da incapacidade funcional, os preditores foram a duração da doença, coerência da doença e qualidadede vida, no grupo de acupunctura, enquanto que a qualidadede vida e as estratégias de alívio activo da dor foram os preditores da incapacidade funcional no grupo de fisioterapia. As implicações do trabalho ao nível da qualidadede vida e incapacidade funcional dos doentes com lombalgia bem como as limitações do estudo são apresentadas e debatidas

    Cold gas in the Intra Cluster Medium: implications for flow dynamics and powering optical nebulae

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    We show that the mechanical energy injection rate generated as the intra-cluster medium (ICM) flows around cold clouds may be sufficient to power the optical and near infra-red emission of nebulae observed in the central regions of a sample of seven galaxy clusters. The energy injection rate is extremely sensitive to the velocity difference between the ICM and cold clouds, which may help to explain why optical and infra-red luminosity is often larger than expected in systems containing AGNs. We also find that mass recycling is likely to be important for the dynamics of the ICM. This effect will be strongest in the central regions of clusters where there is more than enough cold gas for its evaporation to contribute significantly to the density of the hot phase.Comment: 8 pages, 2 figures, accepted for publication in MNRA

    Probing DNA conformational changes with high temporal resolution by Tethered Particle Motion

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    The Tethered Particle Motion (TPM) technique informs about conformational changes of DNA molecules, e.g. upon looping or interaction with proteins, by tracking the Brownian motion of a particle probe tethered to a surface by a single DNA molecule and detecting changes of its amplitude of movement. We discuss in this context the time resolution of TPM, which strongly depends on the particle-DNA complex relaxation time, i.e. the characteristic time it takes to explore its configuration space by diffusion. By comparing theory, simulations and experiments, we propose a calibration of TPM at the dynamical level: we analyze how the relaxation time grows with both DNA contour length (from 401 to 2080 base pairs) and particle radius (from 20 to 150~nm). Notably we demonstrate that, for a particle of radius 20~nm or less, the hydrodynamic friction induced by the particle and the surface does not significantly slow down the DNA. This enables us to determine the optimal time resolution of TPM in distinct experimental contexts which can be as short as 20~ms.Comment: Improved version, to appear in Physical Biology. 10 pages + 10 pages of supporting materia

    Energetics of the molecular gas in the H_2 luminous radio galaxy 3C 326: Evidence for negative AGN feedback

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    We present a detailed analysis of the gas conditions in the H_2 luminous radio galaxy 3C 326 N at z ~ 0.1, which has a low star-formation rate (SFR ~ 0.07 M_⊙ yr^(−1)) in spite of a gas surface density similar to those in starburst galaxies. Its star-formation efficiency is likely a factor ~ 10−50 lower than those of ordinary star-forming galaxies. Combining new IRAM CO emission-line interferometry with existing Spitzer mid-infrared spectroscopy, we find that the luminosity ratio of CO and pure rotational H_2 line emission is factors 10−100 lower than what is usually found. This suggests that most of the molecular gas is warm. The Na D absorption-line profile of 3C 326 N in the optical suggests an outflow with a terminal velocity of ~−1800 km s^(−1) and a mass outflow rate of 30−40 M_⊙ yr^(−1), which cannot be explained by star formation. The mechanical power implied by the wind, of order 10^(43) erg s^(−1), is comparable to the bolometric luminosity of the emission lines of ionized and molecular gas. To explain these observations, we propose a scenario where a small fraction of the mechanical energy of the radio jet is deposited in the interstellar medium of 3C 326 N, which powers the outflow, and the line emission through a mass, momentum and energy exchange between the different gas phases of the ISM. Dissipation times are of order 10^(7−8) yrs, similar or greater than the typical jet lifetime. Small ratios of CO and PAH surface brightnesses in another 7 H_2 luminous radio galaxies suggest that a similar form of AGN feedback could be lowering star-formation efficiencies in these galaxies in a similar way. The local demographics of radio-loud AGN suggests that secular gas cooling in massive early-type galaxies of ≥ 10^(11) M_⊙ could generally be regulated through a fundamentally similar form of “maintenance-phase” AGN feedback

    In-depth inhomogeneities in CIGS solar cells: identifying regions for performance limitations by PIXE and EBS

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    When considering materials to be used as active layers in solar cells, an important required parameter is the proper knowledge of their elemental composition. It should be heavily controlled during growth in order to obtain the desired bandgap and to decrease recombination defects and then increase the solar cell electrical performance. Ion beam analytical techniques and, in particular particle-induced X-ray emission (PIXE) and elastic backscattering spectrometry (EBS), are quite suitable to determine the thickness and composition of such active layers. Furthermore, if these techniques are performed using a nuclear microprobe, lateral and in-depth inhomogeneities can be clearly observed from 2D maps. In many cases, composition variations can be detected from the classical 2D maps obtained from the PIXE spectra. In this work, it is shown how the in-depth variations can also be studied when considering 2D maps reconstructed from the EBS spectra. Such variations are derived from processing conditions and can be related to: i) composition, ii) thickness, iii) roughness, iv) other non-trivial issues. Examples obtained on Cu(In,Ga)Se2 based cells are presented and discussed. Furthermore, the combination of ion beam analytical techniques such as PIXE and EBS is shown to be a competitive and alternative method to those more used and established techniques such as X-ray fluorescence for checking the average composition of the solar cells active layers or SIMS for the determination of elemental depth profile.publishe
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