7,423 research outputs found

    Relevant results from the NA48 experiment

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    We report relevant results from NA48 experiment at CERN SPS. NA48 was proposed in 1990 \cite{proposal} to study direct CP violation in K0→ππK^0\to\pi\pi to a level of accuracy sufficient to resolve the inconclusive status left by the previous measurements performed by NA31 \cite{NA31} and E731 \cite{E731}. In 2002 NA48 published the final result \cite{NA48epsoeps}. Small modification to the experimental setup have allowed NA48 to go forward with an extensive investigation of K0K^0 rare decays and hyperon decays. Some results are already available and reported here together with the final CP violation measurement.Comment: 3 pages, 1 eps figure, XXIII Physics in collisio

    Signatures of rocky planet engulfment in HAT-P-4. Implications for chemical tagging studies

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    Aims. To explore the possible chemical signature of planet formation in the binary system HAT-P-4, by studying abundance vs condensation temperature Tc trends. The star HAT-P-4 hosts a planet detected by transits while its stellar companion does not have any detected planet. We also study the Lithium content, which could shed light on the problem of Li depletion in exoplanet host stars. Conclusions. The exoplanet host star HAT-P-4 is found to be ~0.1 dex more metal rich than its companion, which is one of the highest differences in metallicity observed in similar systems. This could have important implications for chemical tagging studies, disentangling groups of stars with a common origin. We rule out a possible peculiar composition for each star as lambda Boo, delta Scuti or a Blue Straggler. The star HAT-P-4 is enhanced in refractory elements relative to volatile when compared to its stellar companion. Notably, the Lithium abundance in HAT-P-4 is greater than in its companion by ~0.3 dex, which is contrary to the model that explains the Lithium depletion by the presence of planets. We propose a scenario where, at the time of planet formation, the star HAT-P-4 locked the inner refractory material in planetesimals and rocky planets, and formed the outer gas giant planet at a greater distance. The refractories were then accreted onto the star, possibly due to the migration of the giant planet. This explains the higher metallicity, the higher Lithium content, and the negative Tc trend detected. A similar scenario was recently proposed for the solar twin star HIP 68468, which is in some aspects similar to HAT-P-4. We estimate a mass of at least Mrock ~ 10 Mearth locked in refractory material in order to reproduce the observed Tc trends and metallicity.Comment: 5 pages, 6 figures, A&A Letters accepte

    The XMM/BeppoSAX observation of Mkn 841

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    Mkn 841 has been observed simultaneously by XMM and BeppoSAX in January 2001. Due to operational contingency, the 30ks XMM observation was split into two parts, separated by about 15 hours. We first report the presence of a narrow iron line which appears to be rapidly variable between the two pointings, requiring a non-standard interpretation. We then focus on the analysis of the broad band (0.3-200 keV) continuum using the XMM/EPIC, RGS and SAX/PDS data. The Mkn 841 spectrum is well fitted by a comptonization model in a geometry more photon-fed than a simple slab geometry above a passive disk. It presents a relatively large reflection (R>2) which does not agree with an apparently weak iron line. It also show the presence of a strong soft excess wellfitted by a comptonized spectrum in a cool plasma, suggesting the presence of a multi-temperature corona.Comment: 4 pages, 5 figures. Proc. of the meeting: "The Restless High-Energy Universe" (Amsterdam, The Netherlands), E.P.J. van den Heuvel, J.J.M. in 't Zand, and R.A.M.J. Wijers Ed

    Sheathing and Pay Techniques in the Boa Vista 1 Ship (Lisbon, Portugal)

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    Between September 2012 and February 2013, archaeological excavations carried out in the riverside area of Lisbon (Portugal) revealed the remains of two wooden ships: Boa Vista 1 (BV1) and Boa Vista 2 (BV2), both dating from the late seventeenth or early eighteenth century. BV1 ship consists of scattered hull timbers which were damaged and out of their original positions. Some of the ship’s hull features are common in the Mediterranean like a composite keel with butt joints and hook scarfs in the connection between floors and futtocks, while others are well-known Iberian shipbuilding features like the transition between the keel and the sternpost being made through a single piece, the heel. A unique feature was a layer of animal hair between the sheathing and the hull planking. This paper focuses mainly on the study of wooden sheathing, including but not limited to the analysis of its conventional “architectural signatures”. The latest results concerning animal hair identification will also be presented and discussed, showing the added value of multidisciplinary approaches in archaeology.info:eu-repo/semantics/publishedVersio

    Bjerrum pairing correlations at charged interfaces

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    Electrostatic correlations play a fundamental role in aqueous solutions. In this letter, we identify transverse and lateral correlations as two mutually exclusive regimes. We show that the transverse regime leads to binding by generalization of Bjerrum pair formation theory, yielding binding constants from first-principle statistical-mechanical calculations. We compare our theoretical predictions with experiments on charged membranes and Langmuir monolayers and find good agreement. We contrast our approach with existing theories in the strong-coupling limit and on charged modulated interfaces, and discuss different scenarios that lead to charge reversal and equal-sign attraction by macro-ions.Comment: 7 pages, 4 figure

    Strategies to Increase Human Immunodeficiency Virus Testing in Rural Areas of the United States: A Systematic Review

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    Purpose: HIV incidence continues to increase, with a large portion of new diagnoses found in rural areas of the United States. The worsening statistics in rural areas may be attributed to stigma alone and contribute to the lack of testing available for patients. The objective of this systematic review is to identify accessible and feasible strategies to increase HIV testing within the rural communities in the United States. Methods: A systematic literature search of CINAHL Complete, MEDLINE with Full Text, and PsycINFO with restrictions of the English language and rural communities outside of the United States through August 2, 2018. Two independent investigators screened articles using predetermined inclusion and exclusion criteria. This systematic review is registered through PROSPERO: CRD42018108637. Findings: There were 14 different studies with specific interventions attempting to increase the rate of HIV testing in rural communities in the United States. Technology, faith-based stigma reduction, access, and provider interventions emerged as themes regarding HIV testing and stigma improvement. Conclusion: There exists a body of literature that supports a number of specific interventions focusing on access, provider and patient perspective, and ways to decrease stigma that improve HIV testing and could be implemented in rural communities

    BeppoSAX observations of Mrk 841 and Mrk335

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    We present and discuss BeppoSAX observations of Mrk841 and Mrk335, two Seyfert 1 galaxies in which previous observations have established the presence of soft excesses. We confirm the soft excess in both sources, even if for Mrk~841 a warm absorber provides a fit almost as good as the one with a true excess. As far as the hard X-ray continuum is concerned, a Comptonization model provides a fit as good as a power law and a physically sound solution for Mrk841. For Mrk335, the Comptonization model gives a result which is somewhat better on statistical ground, but rather problematic on physical ground. The most interesting results regard the reprocessing components. For Mrk841 we find a very large reflection continuum but an almost normal iron line equivalent width even if, within the errors, a solution in which both components are a factor ~2 larger than expected for an accretion disc is still marginally acceptable. If this is the case, an anisotropy of the primary emission seems the best explanation. On the contrary, in Mrk335 we find a very large iron line EW but a reflection component not accordingly large. In this case, the best solution seems to be in terms of reflection from an ionized disc.Comment: Accepted for publication in A&
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