457 research outputs found
The HARPS search for southern extra-solar planets XXXV. The interesting case of HD41248: stellar activity, no planets?
The search for planets orbiting metal-poor stars is of uttermost importance
for our understanding of the planet formation models. However, no dedicated
searches have been conducted so far for very low mass planets orbiting such
objects. Only a few cases of low mass planets orbiting metal-poor stars are
thus known. Amongst these, HD41248 is a metal-poor, solar-type star on which a
resonant pair of super-Earth like planets has In the present paper we present a
new planet search program that is using the HARPS spectrograph to search for
Neptunes and Super-Earths orbiting a sample of metal-poor FGK dwarfs. We then
present a detailed analysis of an additional 162 radial velocity measurements
of HD41248, obtained within this program, with the goal of confirming the
existence of the proposed planetary system. We analyzed the precise radial
velocities, obtained with the HARPS spectrograph, together with several stellar
activity diagnostics and line profile indicators. A careful analysis shows no
evidence for the planetary system previously announced. One of the signals,
with a period of about 25 days, is shown to be related to the rotational period
of the star, and is clearly seen in some of the activity proxies. The remaining
signal (P~18 days) could not be convincingly retrieved in the new data set. We
discuss possible causes for the complex (evolving) signals observed in the data
of HD41248, proposing that they may be explained by the appearance and
disappearance of active regions on the surface of a star with strong
differential rotation, or by a combination of the sparse data sampling and
active region evolution.Comment: Accepted for publication in A&
Planets around evolved intermediate-mass stars III. Planet candidates and long-term activity signals in six open clusters
[abridged]The aim of this work is to search for planets around evolved stars,
with a special focus on stars more massive than 2\,M in light of
previous findings that show a drop in planet occurrence around stars above this
mass. We used \texttt{kima} to find the Keplerian orbits most capable of
explaining the periodic signals observed in RV data. We also studied the
variation of stellar activity indicators and photometry in order to discard
stellar signals mimicking the presence of planets. We present a planet
candidate in the open cluster NGC3680 that orbits the 1.64\,M star No.
41. The planet has a minimum mass of 5.13M\, and a period of 1155 days.
We also present periodic and large-amplitude RV signals of probable stellar
origin in two more massive stars (5.84 and 3.05\,M in the clusters
NGC2345 and NGC3532). Finally, using new data, we revise the RV signals of the
three stars analysed in our previous paper. We confirm the stellar origin of
the signals observed in NGC2423 No. 3 and NGC4349 No. 127. On the other hand,
the new data collected for IC4651 No. 9122 (1.79\,M) seem to support
the presence of a bona fide planet of 6.22M\, at a period of 744 days,
although more data will be needed to discard a possible correlation with the
CCF-FWHM. The targets presented in this work showcase the difficulties in
interpreting RV data for evolved massive stars. The use of several activity
indicators (CCF-FWHM, CCF-BIS, \ha), photometry, and long-term observations
(covering several orbital and stellar rotational periods) is required to
discern the true nature of the signals. However, in some cases, all this
information is insufficient, and the inclusion of additional data -- such as
the determination of magnetic field variability or RV points in the
near-infrared -- will be necessary to identify the nature of the discovered
signals.Comment: accepted in A&
Planets around evolved intermediate-mass stars III. Planet candidates and long-term activity signals in six open clusters
Planets around evolved intermediate-mass stars III. Planet candidates and long-term activity signals in six open clusters
[abridged]The aim of this work is to search for planets around evolved stars,
with a special focus on stars more massive than 2\,M in light of
previous findings that show a drop in planet occurrence around stars above this
mass. We used \texttt{kima} to find the Keplerian orbits most capable of
explaining the periodic signals observed in RV data. We also studied the
variation of stellar activity indicators and photometry in order to discard
stellar signals mimicking the presence of planets. We present a planet
candidate in the open cluster NGC3680 that orbits the 1.64\,M star No.
41. The planet has a minimum mass of 5.13M\, and a period of 1155 days.
We also present periodic and large-amplitude RV signals of probable stellar
origin in two more massive stars (5.84 and 3.05\,M in the clusters
NGC2345 and NGC3532). Finally, using new data, we revise the RV signals of the
three stars analysed in our previous paper. We confirm the stellar origin of
the signals observed in NGC2423 No. 3 and NGC4349 No. 127. On the other hand,
the new data collected for IC4651 No. 9122 (1.79\,M) seem to support
the presence of a bona fide planet of 6.22M\, at a period of 744 days,
although more data will be needed to discard a possible correlation with the
CCF-FWHM. The targets presented in this work showcase the difficulties in
interpreting RV data for evolved massive stars. The use of several activity
indicators (CCF-FWHM, CCF-BIS, \ha), photometry, and long-term observations
(covering several orbital and stellar rotational periods) is required to
discern the true nature of the signals. However, in some cases, all this
information is insufficient, and the inclusion of additional data -- such as
the determination of magnetic field variability or RV points in the
near-infrared -- will be necessary to identify the nature of the discovered
signals.Comment: accepted in A&
MRI in multiple myeloma : a pictorial review of diagnostic and post-treatment findings
Magnetic resonance imaging (MRI) is increasingly being used in the diagnostic work-up of patients with multiple myeloma. Since 2014, MRI findings are included in the new diagnostic criteria proposed by the International Myeloma Working Group. Patients with smouldering myeloma presenting with more than one unequivocal focal lesion in the bone marrow on MRI are considered having symptomatic myeloma requiring treatment, regardless of the presence of lytic bone lesions. However, bone marrow evaluation with MRI offers more than only morphological information regarding the detection of focal lesions in patients with MM. The overall performance of MRI is enhanced by applying dynamic contrast-enhanced MRI and diffusion weighted imaging sequences, providing additional functional information on bone marrow vascularization and cellularity. This pictorial review provides an overview of the most important imaging findings in patients with monoclonal gammopathy of undetermined significance, smouldering myeloma and multiple myeloma, by performing a 'total' MRI investigation with implications for the diagnosis, staging and response assessment. Main message aEuro cent Conventional MRI diagnoses multiple myeloma by assessing the infiltration pattern. aEuro cent Dynamic contrast-enhanced MRI diagnoses multiple myeloma by assessing vascularization and perfusion. aEuro cent Diffusion weighted imaging evaluates bone marrow composition and cellularity in multiple myeloma. aEuro cent Combined morphological and functional MRI provides optimal bone marrow assessment for staging. aEuro cent Combined morphological and functional MRI is of considerable value in treatment follow-up
Effectiveness and Safety of DirectâActing Antivirals in Hepatitis C Infected Patients With Mental Disorders: Results in Real Clinical Practice
[Abstract]
The aim of this study is to analyze the effectiveness and safety of directâacting antivirals (DAAs) in psychiatric patients with chronic hepatitis C (CHC). Secondary objectives included adherence and drugâdrug interaction (DDIs) evaluations. Prospective observational comparative study carried out during 3 years. Psychiatric patients were included and mental illness classified by a psychiatric team based on clinical records. Main effectiveness and safety variables were sustained virologic response (SVR) at posttreatment week 12 (SVR12) and rate of onâtreatment serious drugârelated adverse events (AEs), respectively. A total of 242 psychiatric and 900 nonpsychiatric patients were included. SVR12 by intentionâtoâtreat (ITT) analysis of psychiatric vs nonpsychiatric patients was 92.6% (95% confidence interval [CI], 89.1â96.1) vs 96.2% (95% CI, 94.9â97.5) (Pâ=â.02). SVR12 by modifiedâITT analysis was 97.8% (95% CI, 95.0â99.3) vs 98.4% (95% CI, 97.5â99.3) (Pâ=â.74). 92.2% of psychiatric patients with mental disorders secondary to multiple drug use (MDSDU) and 93.0% of psychiatric patients without MDSDU vs 96.2% of nonpsychiatric patients reached SVR12 (Pâ=â.05 and Pâ=â.20, respectively). The percentage of adherent patients to DAAs did not show differences between cohorts (Pâ=â.08). 30.2% of psychiatric patients and 27.6% of nonpsychiatric patients presented clinically relevant DDIs (Pâ=â.47). 1.7% vs 0.8% of psychiatric vs nonpsychiatric patients developed serious AEs (Pâ=â.39); no serious psychiatric AEs were present. DAAs have shown a slightly lower effectiveness in psychiatric patients with CHC, as a result of loss of follow up, which justifies the need for integrated and multidisciplinary health care teams. DAAs safety, adherence, and DDIs, however, are similar to that of nonpsychiatric patients
Cylindrically symmetric inhomogeneous dust collapse with a zero expansion component
We investigate a class of cylindrically symmetric inhomogeneous Î-dust
spacetimes which have a regular axis and some zero expansion component.
For Π\neq 0, we obtain new exact solutions to the Einstein equations and show
that they are unique, within that class. For Î = 0, we recover the Senovillaâ
Vera metric and show that it can be locally matched to an EinsteinâRosen type
of exterior. Finally, we explore some consequences of the matching, such as
trapped surface formation and gravitational radiation in the exterior.We thank Jose Senovilla for suggesting solutions of the form (8) and (9) and for other very useful comments which led to substancial improvements in the paper. IB and FM are supported by Portuguese Funds through Fundacao para a Cincia e Tecnologia (FCT), within the Projects UID/MAT/00013/2013 and PTDC/MAT-ANA/1275/2014. FM and NOS acknowledge a grant received from UERJ and thank the warm hospitality from Instituto de Fisica, UERJ, Rio de Janeiro, where a great part of this work was completed. MFAdaSilva acknowledges the financial support from FAPERJ (no. E-26/171.754/2000, E-26/171.533.2002, E-26/170.951/2006, E-26/110.432/2009 and E-26/111.714/2010), Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq) Brazil (no. 450572/2009-9, 301973/2009-1 and 477268/2010-2) and Financiadora de Estudos e Projetos (FINEP) Brazil.info:eu-repo/semantics/publishedVersio
Offshore 1755 CE Lisbon Tsunami deposit in the southern portuguese continental shelf
The importance of tsunami hazard assessment is only possible if a complete dataset of events is
available, allowing the determination of the recurrence intervals of the tsunamis adapted to local
and regional conditions. One possible way to know these intervals is to study the offshore
sedimentary record, looking for sediment remobilised and transported by the incoming tsunami
waves and generated backwash currents. Even if these deposits are not of easy access (and not so
well studied), the tsunami depositional signature has potential to be better preserved than those
located onshore.info:eu-repo/semantics/publishedVersio
TESS asteroseismology of the known red-giant host stars HD 212771 and HD 203949
International audienc
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