785 research outputs found

    Impact of the 3D source geometry on time-delay measurements of lensed type-Ia Supernovae

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    It has recently been proposed that gravitationally lensed type-Ia supernovae can provide microlensing-free time-delay measurements provided that the measurement is taken during the achromatic expansion phase of the explosion and that color light curves are used rather than single-band light curves. If verified, this would provide both precise and accurate time-delay measurements, making lensed type-Ia supernovae a new golden standard for time-delay cosmography. However, the 3D geometry of the expanding shell can introduce an additional bias that has not yet been fully explored. In this work, we present and discuss the impact of this effect on time-delay cosmography with lensed supernovae and find that on average it leads to a bias of a few tenths of a day for individual lensed systems. This is negligible in view of the cosmological time delays predicted for typical lensed type-Ia supernovae but not for the specific case of the recently discovered type-Ia supernova iPTF16geu, whose time delays are expected to be smaller than a day.Comment: 7 pages, 4 figures, published in A&

    On the relevance of large scale pulsed-laser deposition: Evidence of structural heterogeneities in ZnO thin films

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    Pulsed-laser deposition is known as a well-suited method for growing thin films of oxide compounds presenting a wide range of functional properties. A limitation of this method for industrial process is the very anisotropic expansion dynamics of the plasma plume, which induces difficulties to grow on large scale films with homogeneous thickness and composition. The specific aspect of the crystalline or orientation uniformity has not been investigated, despite its important role on oxide films properties. In this work, the crystalline parameters and the texture of zinc oxide films are studied as a function of position with respect to the central axis of the plasma plume. We demonstrate the existence of large non-uniformities in the films. The stoichiometry, the lattice parameter, and the distribution of crystallites orientations drastically depend on the position with respect to the plume axis, i.e., on the oblique incidence of the ablated species. The origin of these non-uniformities, in particular, the unexpected tilted orientation of the ZnO c-axis may be attributed to the combined effects of the oblique incidence and of the ratio between oxygen and zinc fluxes reaching the surface of the growing film

    Probing compact dark matter objects with microlensing in gravitationally lensed quasars

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    The microlensing signal in the light curves of gravitationally lensed quasars can shed light on the dark matter (DM) composition in their lensing galaxies. Here, we investigate a sample of six lensed quasars from the most recent and best COSMOGRAIL observations: HE 1104-1805, HE 0435-1223, RX J1131-1231, WFI 2033-4723, PG 1115+080, and J1206+4332, yielding a total of eight microlensing light curves, when combining independent image pairs and typically spanning ten years. We explore the microlensing signals to determine whether the standard assumptions on the stellar populations are sufficient to account for the amplitudes of the measured signals or whether additional microlenses are needed. We use the most detailed lens models to date from the H0LiCOW/TDCOSMO collaboration to derive the microlensing parameters, such as the convergence, shear, and stellar/dark matter mass fraction at the position of the quasar images. We use these parameters to generate simulated microlensing light curves. Finally, we propose a methodology based on the Kolmogorov-Smirnov test to verify whether the observed microlensing amplitudes in our data are compatible with the most standard scenario, whereby galaxies are composed of stars as compact bodies and smoothly distributed DM. Given our current sample, we show that the standard scenario cannot be rejected, in contrast with previous results by Hawkins (2020a, A&amp;A, 633, A107), claiming that a population of stellar mass primordial black holes (PBHs) is necessary to explain the observed amplitude of the microlensing signal in lensed quasar light curves. We further estimate the number of microlensing light curves needed to effectively distinguish between the standard scenario with stellar microlensing and a scenario that describes that all the DM contained in galaxies is in the form of compact objects such as PBHs, with a mean mass of 0.2 Mo. We find that about 900 microlensing curves from the Rubin Observatory will be sufficient to discriminate between the two extreme scenarios at a 95% confidence level.</p

    UV to NIR photon conversion in Nd-doped rutile and anatase titanium dioxide films for silicon solar cell application

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    Undoped and Nd-doped titanium dioxide anatase and rutile films have been grown by pulsed-laser deposition at 700 °C under 0.1 mbar O2. By selecting adequate substrates, TiO2 films doped with 1, 2 or 5 at.% Nd were grown and constituted with polycrystalline rutile, highly oriented (2 0 0) rutile film, or oriented (0 0 4) anatase. An UV to NIR photon conversion is evidenced in the films. Indeed, intense and well-resolved emission lines from Nd3+ have been observed upon excitation above the TiO2 bandgap at room temperature. The sensitised emission of Nd3+ is found to be much efficient in rutile than in anatase structure. Low temperature photoluminescence measurements lead to fine resolved peaks corresponding to the Nd3+ 4f transitions with different spectral characteristic according to the host matrix used. Photoluminescence dependence temperature evidences that the light emission from Nd3+ in anatase-based films is probably influenced by the presence of self-trapped excitons or by orbital interaction. Mechanisms of sensitisation host to Nd3+ are proposed for both matrixes. Finally, the Nd dopant concentration and the microstructure of TiO2 rutile films are found to affect the photoluminescence emission intensity. Rutile film (2 0 0) oriented is the most adapted host matrix to sensitise 1 at.% Nd3+ ions for an emission around 1064 nm making such Nd-doped layers interesting for photon conversion by down shifting process

    What Attracts Men Who Batter to Their Partners? An Exploratory Study

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    Men who batter, because of particular personality traits and sense of entitlement, may select partners whom they perceive will be dependent on them, meet their emotional needs, or be “objects” of physical attractiveness. During treatment intake, 181 offenders responded to the question, “What attracted you to her (your partner)?” We explored whether men who mentioned their own needs or her physical traits would engage in more frequent and severe violence and would have specific forms of personality disorder dimensions or personality traits. Six categories of attraction, including “her physical traits” and “his needs,” were derived from the men’s responses. The results showed that men who focused on their partners’ physical attractiveness were more likely to be violent after treatment. Men who cited their own needs for their attraction had higher scores on borderline personality, alcohol abuse, and psychotic thinking and lower scores on compulsive-conformingPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/89970/1/Saunders-Kurko-Barlow-Crane 2011 What Attracts Men Who Batter to Their Partners JIV.pd

    Personality disorders and psychosocial problems in a group of participants to therapeutic processes for people with severe social disabilities

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    <p>Abstract</p> <p>Background</p> <p>Homeless people have high dropout rates when they participate in therapeutic processes. The causes of this failure are not always known. This study investigates whether dropping-out is mediated by personality disorders or whether psychosocial problems are more important.</p> <p>Method</p> <p>Eighty-nine homeless people in a socio-laboral integration process were assessed. An initial interview was used, and the MCMI II questionnaire was applied to investigate the presence of psychosocial disorders (DSM-IV-TR axis IV). This was designed as an <it>ex post-facto </it>prospective study.</p> <p>Results</p> <p>Personality disorders were very frequent among the homeless people examined. Moreover, the high index of psychosocial problems (axis IV) in this population supported the proposal that axis IV disorders are influential in failure to complete therapy.</p> <p>Conclusion</p> <p>The outcomes of the study show that the homeless people examined presented with more psychopathological symptoms, in both axis II and axis IV, than the general population. This supports the need to take into account the comorbidity between these two types of disorder among homeless people, in treatment and in the development of specific intervention programs. In conclusion, the need for more psychosocial treatments addressing the individual problems of homeless people is supported.</p

    COSMOGRAIL: XVII. Time delays for the quadruply imaged quasar PG 1115+080

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    Indexación: Scopus.Acknowledgements. The authors would like to thank R. Gredel for his help in setting up the program at the ESO MPIA 2.2 m telescope, and the anonymous referee for his or her comments on this work. This work is supported by the Swiss National Fundation. This research made use of Astropy, a community-developed core Python package for Astronomy (Astropy Collaboration et al. 2013, 2018) and the 2D graphics environment Matplotlib (Hunter 2007). K.R. acknowledge support from PhD fellowship FIB-UV 2015/2016 and Becas de Doctorado Nacional CONICYT 2017 and thanks the LSSTC Data Science Fellowship Program, her time as a Fellow has benefited this work. M.T. acknowledges support by the DFG grant Hi 1495/2-1. G. C.-F. C. acknowledges support from the Ministry of Education in Taiwan via Government Scholarship to Study Abroad (GSSA). D. C.-Y. Chao and S. H. Suyu gratefully acknowledge the support from the Max Planck Society through the Max Planck Research Group for S. H. Suyu. T. A. acknowledges support by the Ministry for the Economy, Development, and Tourism’s Programa Inicativa Científica Milenio through grant IC 12009, awarded to The Millennium Institute of Astrophysics (MAS).We present time-delay estimates for the quadruply imaged quasar PG 1115+080. Our results are based on almost daily observations for seven months at the ESO MPIA 2.2 m telescope at La Silla Observatory, reaching a signal-to-noise ratio of about 1000 per quasar image. In addition, we re-analyze existing light curves from the literature that we complete with an additional three seasons of monitoring with the Mercator telescope at La Palma Observatory. When exploring the possible source of bias we considered the so-called microlensing time delay, a potential source of systematic error so far never directly accounted for in previous time-delay publications. In 15 yr of data on PG 1115+080, we find no strong evidence of microlensing time delay. Therefore not accounting for this effect, our time-delay estimates on the individual data sets are in good agreement with each other and with the literature. Combining the data sets, we obtain the most precise time-delay estimates to date on PG 1115+080, with Δt(AB) = 8.3+1.5 -1.6 days (18.7% precision), Δt(AC) = 9.9+1.1 -1.1 days (11.1%) and Δt(BC) = 18.8+1.6 -1.6 days (8.5%). Turning these time delays into cosmological constraints is done in a companion paper that makes use of ground-based Adaptive Optics (AO) with the Keck telescope. © ESO 2018.https://www.aanda.org/articles/aa/abs/2018/08/aa33287-18/aa33287-18.htm

    Shareholder Protection: A Comparative Review of the Corporate Legal / Regulatory Regimes in the UK and Nigeria

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    Foreign investment is a major source of the capital that Nigeria and other developing markets need to promote economic activities and drive economic development. While profit mainly drives the decision to invest abroad, such decisions are also influenced by the safety of any actual investments made. Thus, investors are interested in the laws and regulations that offer them protection against corporate insider opportunism. In Nigeria, the relationship between corporate actors is mainly regulated by the Companies and Allied Matters Act (CAMA). This article investigates the corporate legal and regulatory protection for corporate shareholders in Nigeria and the UK. Comparing the corporate regulatory regime in the two jurisdictions, this article argues that the identified weaknesses in the Nigerian regulatory framework negatively impact the growth of foreign investment in the country. In view of these weaknesses, the article suggests a major review of CAMA and other regulatory instruments with a view to addressing the protection of small investors and “outsiders”, such as foreign investors

    COSMOGRAIL XVIII: time delays of the quadruply lensed quasar WFI2033-4723

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    We present new measurements of the time delays of WFI2033-4723. The data sets used in this work include 14 years of data taken at the 1.2m Leonhard Euler Swiss telescope, 13 years of data from the SMARTS 1.3m telescope at Las Campanas Observatory and a single year of high-cadence and high-precision monitoring at the MPIA 2.2m telescope. The time delays measured from these different data sets, all taken in the R-band, are in good agreement with each other and with previous measurements from the literature. Combining all the time-delay estimates from our data sets results in Dt_AB = 36.2-0.8+0.7 days (2.1% precision), Dt_AC = -23.3-1.4+1.2 days (5.6%) and Dt_BC = -59.4-1.3+1.3 days (2.2%). In addition, the close image pair A1-A2 of the lensed quasars can be resolved in the MPIA 2.2m data. We measure a time delay consistent with zero in this pair of images. We also explore the prior distributions of microlensing time-delay potentially affecting the cosmological time-delay measurements of WFI2033-4723. There is however no strong indication in our measurements that microlensing time delay is neither present nor absent. This work is part of a H0LiCOW series focusing on measuring the Hubble constant from WFI2033-4723.Comment: Submitted to Astronomy and Astrophysic
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