217 research outputs found
Spectroscopic evidence for the binary nature of AM CVn
We analysed archival spectroscopic data of AM CVn taken with the William
Herschel Telescope in 1996. In the literature two orbital periods for AM CVn
are proposed. A clear S-wave in the HeI 4471, 4387 and 4143 \AA lines is
revealed when the spectra are folded on the 1029 s period. No signature of this
S-wave is seen when folded on 1051 s. Doppler tomography of the line profiles
shows a clear signature of the hotspot. Using this we can constrain the value
of K_2 to lie between 210 and 280 km/s. Our work confirms the binary nature of
AM CVn beyond any doubt, establishes 1028.73 s as the true orbital period and
supports the interpretation of AM CVn as a permanent superhump system.Comment: Accepted by MNRA
The Faint Sky Variability Survey I: Goals and data reduction process
The Faint Sky Variability Survey is aimed at finding photometric and/or
astrometric variable objects in the brightness range between 16<V<24 on
timescales between tens of minutes and years with photometric precisions
ranging from 3 millimagnitudes for the brightest to 0.2 magnitudes for the
faintest objects. An area of ~23 square degrees, located at mid and high
Galactic latitudes, has been covered using the Wide Field Camera on the 2.5m
Isaac Newton Telescope on La Palma. Here we describe the main goals of the
Faint Sky Variability Survey and the data reduction process.Comment: Accepted by MNRAS, 8 pages, 6 figure + 3 as JPEG
Graviton Mass from Close White Dwarf Binaries Detectable with LISA
The arrival times of gravitational waves and optical light from orbiting
binaries provide a mechanism to understand the propagation speed of gravity
when compared to that of light or electromagnetic radiation. This is achieved
with a measurement of any offset between optically derived orbital phase
related to that derived from gravitational wave data, at a specified location
of one binary component with respect to the other. Using a sample of close
white dwarf binaries (CWDBs) detectable with the Laser Interferometer Space
Antenna (LISA) and optical light curve data related to binary eclipses from
meter-class telescopes for the same sample, we determine the accuracy to which
orbital phase differences can be extracted. We consider an application of these
measurements involving a variation to the speed of gravity, when compared to
the speed of light, due to a massive graviton. For a subsample of 400
CWDBs with high signal-to-noise gravitational wave and optical data with
magnitudes brighter than 25, the combined upper limit on the graviton mass is
at the level of eV. This limit is two orders of
magnitude better than the present limit derived by Yukawa-correction arguments
related to the Newtonian potential and applied to the Solar-system.Comment: revised version, 8 pages, 5 figures, to appear in PR
Inflammatory activity assessment by F18 FDG-PET/CT in persistent symptomatic sarcoidosis
SummaryBackgroundEstablishing inflammatory activity in sarcoidosis patients with persistent disabling symptoms is important. Whole body F18-FDG PET/CT (PET) appeared to be a sensitive method to detect inflammatory activity in newly diagnosed symptomatic sarcoidosis. The aim was to assess the presence of inflammatory activity using PET in sarcoidosis patients with unexplained persistent disabling symptoms and the association between PET findings and serological inflammatory markers.MethodsSarcoidosis patients who underwent a PET between June 2005 and June 2010 (n = 89), were retrospectively included. All PET scans were examined and positive findings were classified as thoracic and/or extrathoracic. As serological markers of inflammatory activity angiotensine-converting enzyme (ACE), soluble interleukin-2 receptor (sIL-2R), and neopterine were considered.ResultsIn 65/89 (73%) of the studied patients PET was positive, 52 of them (80%) had serological signs of inflammatory activity. In 14/15 patients with a Chest X-ray stage IV PET was positive. In 80% of the PET positive patients extrathoracic inflammatory activity was found. Sensitivity of combined serological inflammatory markers for the presence of inflammatory activity as detected by PET was 80%, specificity 100%, positive predictive value 100%, negative predictive value 65%.ConclusionsThe majority of sarcoidosis patients with persistent disabling symptoms, even those with radiological stage IV, had PET positive findings with remarkably 80% extrathoracic lesions. In 20% PET was positive without signs of serological inflammatory activity. PET appeared to be of additional value to assess inflammatory activity in patients with persistent symptoms in the absence of signs of serological inflammatory activity and to detect extrathoracic lesions
Bortezomib maintenance after R-CHOP, cytarabine and autologous stem cell transplantation in newly diagnosed patients with mantle cell lymphoma, results of a randomised phase II HOVON trial
Rituximab-containing induction followed by autologous stem cell transplantation (ASCT) is the standard first-line treatment for young mantle cell lymphoma patients. However, most patients relapse after ASCT. We investigated in a randomised phase II study the outcome of a chemo-immuno regimen and ASCT with or without maintenance therapy with bortezomib. Induction consisted of three cycles R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone), two cycles high-dose cytarabine, BEAM (carmustine, etoposide, cytarabine, melphalan) and ASCT. Patients responding were randomised between bortezomib maintenance (1·3 mg/m2 intravenously once every 2 weeks, for 2 years) and observation. Of 135 eligible patients, 115 (85%) proceeded to ASCT, 60 (44%) were randomised. With a median follow-up of 77·5 months for patients still alive, 5-year event-free survival (EFS) was 51% (95% CI 42–59%); 5-year overall survival (OS) was 73% (95% CI 65–80%). The median follow-up of randomised patients still alive was 71·5 months. Patients with bortezomib maintenance had a 5-year EFS of 63% (95% CI 44–78%) and 5-year OS of 90% (95% CI 72–97%). The patients randomised to observation had 5-year PFS of 60% (95% CI, 40–75%) and OS of 90% (95% CI 72–97%). In conclusion, in this phase II study we found no indication of a positive effect of bortezomib maintenance after ASCT
Treatment of Older Patients with Mantle-Cell Lymphoma
BACKGROUND: The long-term prognosis for older patients with mantle-cell lymphoma is poor. Chemoimmunotherapy results in low rates of complete remission, and most patients have a relapse. We investigated whether a fludarabine-containing induction regimen improved the complete-remission rate and whether maintenance therapy with rituximab prolonged remission. METHODS: We randomly assigned patients 60 years of age or older with mantle-cell lymphoma, stage II to IV, who were not eligible for high-dose therapy to six cycles of rituximab, fludarabine, and cyclophosphamide (R-FC) every 28 days or to eight cycles of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) every 21 days. Patients who had a response underwent a second randomization to maintenance therapy with rituximab or interferon alfa, each given until progression. RESULTS: Of the 560 patients enrolled, 532 were included in the intention-to-treat analysis for response, and 485 in the primary analysis for response. The median age was 70 years. Although complete-remission rates were similar with R-FC and R-CHOP (40% and 34%, respectively; P=0.10), progressive disease was more frequent with R-FC (14%, vs. 5% with R-CHOP). Overall survival was significantly shorter with R-FC than with R-CHOP (4-year survival rate, 47% vs. 62%; P=0.005), and more patients in the R-FC group died during the first remission (10% vs. 4%). Hematologic toxic effects occurred more frequently in the R-FC group than in the R-CHOP group, but the frequency of grade 3 or 4 infections was balanced (17% and 14%, respectively). In 274 of the 316 patients who were randomly assigned to maintenance therapy, rituximab reduced the risk of progression or death by 45% (in remission after 4 years, 58%, vs. 29% with interferon alfa; hazard ratio for progression or death, 0.55; 95% confidence interval, 0.36 to 0.87; P=0.01). Among patients who had a response to R-CHOP, maintenance therapy with rituximab significantly improved overall survival (4-year survival rate, 87%, vs. 63% with interferon alfa; P=0.005). CONCLUSIONS: R-CHOP induction followed by maintenance therapy with rituximab is effective for older patients with mantle-cell lymphom
Astronomical Distance Determination in the Space Age: Secondary Distance Indicators
The formal division of the distance indicators into primary and secondary leads to difficulties in description of methods which can actually be used in two ways: with, and without the support of the other methods for scaling. Thus instead of concentrating on the scaling requirement we concentrate on all methods of distance determination to extragalactic sources which are designated, at least formally, to use for individual sources. Among those, the Supernovae Ia is clearly the leader due to its enormous success in determination of the expansion rate of the Universe. However, new methods are rapidly developing, and there is also a progress in more traditional methods. We give a general overview of the methods but we mostly concentrate on the most recent developments in each field, and future expectations. © 2018, The Author(s)
Search for gravitational waves from Scorpius X-1 in the second Advanced LIGO observing run with an improved hidden Markov model
We present results from a semicoherent search for continuous gravitational waves from the low-mass x-ray binary Scorpius X-1, using a hidden Markov model (HMM) to track spin wandering. This search improves on previous HMM-based searches of LIGO data by using an improved frequency domain matched filter, the J-statistic, and by analyzing data from Advanced LIGO's second observing run. In the frequency range searched, from 60 to 650 Hz, we find no evidence of gravitational radiation. At 194.6 Hz, the most sensitive search frequency, we report an upper limit on gravitational wave strain (at 95% confidence) of h095%=3.47×10-25 when marginalizing over source inclination angle. This is the most sensitive search for Scorpius X-1, to date, that is specifically designed to be robust in the presence of spin wandering. © 2019 American Physical Society
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