7,672 research outputs found
Relevant results from the NA48 experiment
We report relevant results from NA48 experiment at CERN SPS. NA48 was
proposed in 1990 \cite{proposal} to study direct CP violation in
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 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
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
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)
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
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
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
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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